1-That's not a knife-this is a knife
Certain countries, cities and towns have banned swords and other such "military-grade" weapons but allow short knives for eating one's food and self defence. Designed for and used by the King's Hands to infiltrate other Kingdoms and Queendoms , one or two of these have been lost and ended up in the public domain. The sheath looks like it holds a short blade just six inches long but when the weapon is drawn it is in fact a three foot long sword capable in the right hands of scything a human down. The sword itself is not magical, but the scabbard contains a small bubble of extra-planar space within it.
2-This sheath keeps your sword shining
One of several low-tech items that could be mass-produced with ease for the armed forces of Vallermoore this weapon helps to micro-clean weapons, repairing minor notches and cleaning off any blood that remains once the weapon has been wiped clean on grass or some other such thing, making the swords last a lot longer then they otherwise would, preventing rust and pitting of the metal. The generals like it because it saves money for more important things, the officers and NCO's like it as it makes their men look good,and the men like it as it helps keep them from being punished by docked pay or being beaten for the crime of having dirty weapons.
3-Keep it under your hat
Edward Minton, known by his friends and clients as the Mad Hatter, sells hats both legally and above board in his hat shop, and secretly in The Black Market. The hats he sells secretly have one very big difference, they have hidden compartments in the lining not at once visible to the naked eye, containing hidden weapons. The bigger the hat, the bigger the weapon hidden inside. A beret might have poison needles or a short throwing knife or dagger, a top hat could contain a short sword inside. In this way weapons can be sneaked into areas where they are banned, such as the local noble's court or even in some cases into prisons.
4-Where did I put the damm thing?
This sheath has an invisibility spell cast upon it and the spell also covers up the handle of the weapon inside it and even when the sword is drawn it remains invisible for the next five minutes . It was invented by Sir Edmund Verney for the secret service of Queen Yocasta, as it is far too expensive to mass produce for the army and navy but was perfect for assassins. When it is left somewhere the owner must remember where it is or he or she put it or it will be a long frustrating search before it is finally found.
5- It's a kind of magic
This sheath makes whatever weapon is put into it magical. It does not turn it into an Uber-Sword of Doom; in stats terms it does not even make the weapon into a +1 sword. But it does give it the important ability to harm creatures like the Elemental that can only be harmed by magical weapons and so may save the life of it's owner some day.
6-See this? It's the magical sword of Kaboom! Don't make me have to use it.
This sheath glows brightly in the dark and so can be used to light the way or even to read by. As well as that many people will be fooled into thinking that the sword within is also magical, as surely the blade within must be glowing enough to make the scabbard glow. Should the sword be drawn however it will be revealed not to be glowing after all, so it is best used in a fight situation as a bluff in the hope that the other fighter or fighters will get scared and back down before weapons are drawn.
"Dropped your sword in combat? Need to avoid getting pierced like a pincushion? Well, the trusty Sword-Scabbard is for you. The lower foot is of wood and has a non-slip carved ivory inlay for a good strong grip, and the rest of it is a hollow sword in it's own right, with a sharp point and a sharp blade on each edge. With this, you get a second chance to make a first impression-in your attacker's chest. Buy the Sword-Scabbard today;you won't be sorry, but your attacker will be."
In fact what the advertiser has not told you is that the Sword-Scabbard being hollow, can only take a certain number of blows from a weapon before being bent out of shape or even broken. However, if the fight is swift it can indeed be the difference between life and death as it can take about ten hard blows before being damaged.
8-These boots are made for kicking
On the surface a study pair of boots, when the wearer clicks his heels together a short sharp blade comes out from each one, good for slicing a rival's ankle tendons open or lacerating a kneecap. If the wearer is feeling unsporting he or she can apply poison to the blades or rub them in feaces before using them, so that the wounds given get infected. In this case, the boots are the sheaths. Getting the blades back into the shoes again is a bit of a problem and to hide them again requires good cobbling skills. These boots really are made for kicking.
9-Don't draw this in anger.
The sheath acts like one of the Blade Hands. When drawn, the sheath makes a racket until a member of law enforcement gets there and flashes white if drawn by mistake, green if used in self defence and red if used to atack someone. So far 30 Cities have made it the law that weapons have to be carried in these sheaths to be legal within the city limits, with jail time or worse for violators of this law.
10-The bank of Scabbard
This sheath contains a money pouch within it to help hide one's money from pickpockets and other non-violent criminals. Other then that it is just a normal sheath.
This sheath has a fire spell storied inside it, that will not go off whilst the sheath holds a weapon or indeed anything else inside it. But when emptied and held in the hand with the open part pointing at a target, and the word "Fire" is said, a small but powerful fireball will come out and ignite the target. It can be used to kill, to maim, for arson or just to light a fire in an emergency such as extreme cold when a fire is needed to stay alive. It has two uses in it, after the second use it rapidly crumbles into ash so that it cannot be found by the police or other law enforcement organization and link it's owner to it's use.
This sheath reacts to violence against it's owner by creating a weak force field. Whilst it does not last very long, it protects against a stab in the back and for some time against an attempt to slit the throat, giving it's owner the time needed to pull out a weapon, flee or both.
Whilst it grants no bonuses in combat, if somebody of either gender makes love to someone of the opposite gender with this at his or her side, there will be no danger of pregnancy. All the safety of a condom without the mess or the loss of sensation and unlike a condom it can be used over and over again.
14-Sheath of Cool
The only magical power that this sheath has is to change colour and texture to fit in with the clothing that the owner is wearing. Strictly one for the vain.
This sheath, when a code word is said, will sing a selection of songs for it's owner when he or she is alone or traveling on the road. Because it would annoy everyone otherwise, another code word shuts off the singing when silence or just quiet is needed.
16-Calling All Guards
This sheath, meant for military or City Guard use, has been enchanted so by speaking into it, it can be used as a radio and those with this kind of sheath can hear what the person is saying from miles away. To speak into it the weapon needs to be out of it's sheath, and most police forces and military units impose strict discipline so people don't talk at once and scramble the messages.
This sheath was made by a traitor leatherworker. Over time, it slowly damages the sword within it, pitting the surface with tiny holes, rusting the metal inside and making it brittle, to the point that when used in combat it will snap in two after a few hard blows. The king for which this sheath was made for perished in battle because of it, and with a sense of humour it was buried in his tomb with him to punish whatever grave robber would steal it from the grave not knowing what it did to swords placed within it.
18-Never get lost with this
This sheath has a compass set in it. Sadly, the iron in an iron sword might or might not cause the needle in it to spin wildly, meaning you have to draw the weapon to make your compass work properly.
This sheath has a second layer in it that can be filled with water and make a handy water flask, that can make a big difference in deserts.
Whilst of little use in bright light, in darkness or shadows this creates an aura out of them to hide the wearer from sight. If the wearer also keeps still he or she is almost impossible to see in the dark. The sort of thing that ninjas would use to get closer to a target.
21-Sheath of reanimation
When wearing this at his or her side, the owner cannot die violently. However, he or she will still feel all the pain of any wounds given, and if they get infected will constantly feel the need to drink water and suffer the other pains of infection. Any fatal blow means that if the belt is ever taken off the owner will die, unless the wound is healed, and if hurt badly enough the owner may well want to take it off to stop the pain. Should the heart stop whilst wearing this, then unless it is somehow restarted quickly the owner will decay over time, losing sight first, then the power of speech,then that of hearing,then finally the sense of touch, yet will still be alive unless the scabbard is removed.
This sheath, at the first sign of danger, shoots the sword into your hand. Whilst this can save your life in an ambush, it is otherwise often a real pain in the ass. First, someone not used to this could easily drop their sword on the ground when they most need it, or even in really unlucky cases end up dropping it point-first on their own foot. Worse then that the maker had a mild dislike of police officers and nobles; when one of these comes near, the sheath will expel the sword often ending up with it's user facing serious criminal charges or worse, getting into a fight with a noble's well armed, well trained bodyguards.
23-Sheath made of Orc skin
It is what it is, a sheath made of the skin of an Orc killed in battle. Orc haters will be pleased at the sight and may well ask the owner how he or she got it; Orcs may well decide to kill the bearer of this on sight, as who but an Orc hater would use this to hold his or her weapon?
Whilst of little value by itself, some magical weapons have a limited number of charges before the magic runs out, and this sheath can recharge them at a rate of one charge every hour up to the maximum number of charges that the weapon has. So the Mega Wand of Fireballs from the distant past found in King Eric's tomb can become a mighty weapon once more.
In the vast majority of countries mages and witches are revered and respected, but not in all of them. A minority fear and hate magic users for religious or other reasons and jail or execute those they catch within their borders. Wearing this, a magic user can mask their aura but can still use their magic when they really want or need to.
26-Sheath of Fear
This sheath casts a very weak fear spell on others. It has to be weak, as a strong one would make it impossible to interact with people normally;they would either flee or fight out of terror. However it might make the difference between a brawl starting and the other person backing down. When whole armies are equipped with these the sheer numbers of them gathered in one area causes a big Fear spell to be cast,weakening the morale of the opposing army.
27-What's going on here?
Meant for law enforcement use and normally found on the belt of a City Guard, this sheath will bend to show when someone within six feet of it is carrying illegal weapons or drugs. Certain customs officers might also have one of these to help detect smugglers.
Certain high ranking and foppish nobles have these made for them and sometimes buried with them. They normally are not magical but can be worth quite a bit of money...if that is, one can find an underworld fence willing to buy them. Unless of course the PCs are wealthy nobles who can buy and sell these things perfectly legally.
Army officers and City Guards find this sheath gives them a bonus when trying to calm riots, give orders and the like. It won't protect it's owner from something or someone determined to attack, but it does deter the wavering and the unsure and can make the difference between a fight breaking out or not. At all times the owner must remain professional or it will cease to help him or her.
Another way of sneaking blades into areas where they are banned, this sheath is concealed within the outer lining of a suitcase,within easy reach if needed. To get the blade out the suitcase needs to be pointed down and shaken hard and the sword will slide out of it.
Additional Ideas (1)
31: Adder Sheath
This sheath is lined with a thick layer of poison- any blade kept within is drawn entirely coated. Care must be taken not to poison one's self when using this sheath.
32: Double Trouble Sheath
This sheath contains a separate compartment for a dagger- once the main compartment is drawn, the sheath situates the dagger so it can be drawn next without any pause.