Non-Magical Sword Problems
Even the best sword,such as a blade made for a king, may break in battle, and a lesser blade is more likely to suffer this fate. It may be that the sword was shoddily made, is very old and has been in many combats, strikes something a sword was not designed to face, like a heavy oak table, or is facing a heavier weapon then itself and is having great pressure put on it with every blow.
On the stage and in movies sword fighters often parry with the sharp edge of the blade, but in reality, edge parrying with sharp swords only happened if that was the only way to avoid being killed or seriously hurt. No sensible sword owner would deliberately parry with the sharp edges of his or her sword,because those sharp edges would soon be chipped, nicked and notched until it was unable to cut anything or anyone.
With Western swords they preferred to dodge or if that was impossible, to catch the opponent's blade on the flat of their own blade or with a shield, cloak or parrying dagger. With the katana, they preferred to use either the flat of the blade or the blunt back of the blade. Of course there must have been times in a frantic fight to the death that edge met edge, but it was only done on purpose when it was the only way to fend off the enemy's sword.
The sword in this case is so notched up that it needs work from a blacksmith before it can be used to cut again. Perhaps it met a Notcher on the field of battle.
3-Piece of History
The sword is made of bronze, and was most likely robbed from some old tomb, taken from the dusty bony hands of a king of old, or perhaps won from a barrow wight or a Bandage Beast. Whilst it is green when found, this patina can easily be cleaned off to make it shine and gleam as if it was fresh from the furnace. It may look good but the reason why bronze weapons gave way to iron ones is because bronze is a softer metal and easily bends or worse when struck with iron.
The blade was exposed to water and was not dried and has become orange with rust. Whilst it may add tetanus to the other horrors of warfare, it is brittle, unslightly and likely to break in battle.
The blade is ridiculously long, thick and heavy. Perhaps it is a ceremonial weapon only, or it was enchanted but lost it's magic, or it is a Great Greatsword belonging to an Ogre or one of The Volgotoi. A human, dwarf or elf would be lucky to even be able to pick it up, let alone use it to fight with.
For some reason there are strict laws banning this kind of sword. Perhaps the blade is poisoned, or barbed, or if magical raises those it kills as undead zombies under the control of the sword's owner. For whatever reason, the laws of the country and those who enforce the laws are very unfriendly towards anyone caught with one of these swords.
The blade of this sword is made of pure silver with a hilt of pure gold. Where do I start with the problems with this?
The blade is weak and will soon bend or break in battle. It is very hard to sharpen, the cross guard or basket hilt will break with one good blow rather then protect the hand, thieves and bandits will come after it and it will get the normally unwelcome attention of law enforcement. It is a ceremonial sword only.
On the plus side it will harm magical creatures that can only be harmed with silver weapons and it looks gorgeous, but unless you are going to be presented at court or know you will be facing something that can only be harmed by silver, do yourself a favour and leave it locked up in a safe at home.
This sword has three long blades, two at 45 degree angles to each other and in the hands of a gladiator who has spent a long time training with this against a wooden post is a truly fearsome weapon indeed. To the average user, it is clumsy to use at best.
After a major revolt of the poor against the rich was crushed, swords were banned for all non nobles without exceptions. Perhaps non nobles cannot legally bear arms at all, or perhaps clubs and knives are okay but not swords and other such weapons of war. If caught with a sword the penalty is to hang in a gibbet alive until death and until your body is just a pile of bones.
10-Stuck in the scabbard
Perhaps rust has got to this sword or maybe it was glued into the scabbard deliberately, either as part of a murder plot or because it is a court sword and the monarch was fed up with his or her courtiers illegally duelling or feared assassination or both. No matter how hard it is pulled it will not come out of the scabbard.Awkward in a fight.
The sword is long and thin like a fencing foil, with a very sharp point on it but no sharp edge worth mentioning. Against swords designed to both thrust and cut the sword's owner is at a disadvantage.
The sword has a sharp cutting edge but no sharp point. Against swords designed to both thrust and cut the sword's owner is at a disadvantage.
The sword is a masterwork blade but it has been stolen from a wealthy and powerful noble, and as it is a family
heirloom, he is desperate to get it back, and has sent armed retainers to track down the thief and mete out his revenge.
This weapon was made by the merpeople from narwhal ivory with sharp points of coral stuck into it. Unfortunately it has long since dried up since it was washed up on the shore and become weak and brittle to the point where a few blows would break it in two. If soaked for long enough in seawater it will regain it's quality and flexibility.
Magical Sword Problems
This sword turns even a novice into a master swordsman or swordswoman but, the magic is powered by the life force of the unfortunate owner. And it has been known for someone to win his fight with ease, only to drop dead soon afterwards, drained to death by the magical sword.
16-Oh, shut up!
The original owner of this sword was a battle-mage and he cast a spell on it so that it could play music. One day he went into battle with his sword loudly singing songs of war and tragically was killed. And the secret of how to turn off the music of the sword unfortunately died with him. The sword had to be buried in his grave with him and those who stand close to the grave can still hear it singing war songs in an endless loop. No grave robbers have stolen it because nobody would want to own a sword that constantly and loudly sings all the time.
Meant only for the afterlife, this fine sword violently explodes in sunlight. Grave robbers beware! It works well in the dark, however.
A witch cursed this sword after it was used to kill her father. What exactly the curse is, is up to the GM, but whatever it is, the results will not be pleasant.
This magical sword glows brightly (and can harm those who can only be harmed by magical weapons) but has no other magical abilities at all.
This sword is encased in one of the Blade Hands with the result that if drawn in anger, it will glow red and make a horrible noise until the city guards or the police force arrive on the scene to deal with the culprit.
This sword has had certain scrying spells placed upon it, and records everything spoken when worn.A code word will make it speak and repeat everything it has recorded to the spy who knows about it. Important war plans have been uncovered in this way.
If the society in which the sword was forged and enchanted was deeply sexist towards one of the genders, then it may jerk in the hand either to resist being used by the opposite gender or, if it faces the opposite gender in battle, to do as much damage as possible. A desert scimitar might have a hatred of women whilst a sword made by Amazon warriors might have a hatred of men.
Something went very wrong with the enchantment of this sword and it turned it into a coward, to the point that it flinches from combat, begs for mercy and is near-useless as a weapon to fight with.
Whoever holds this sword finds it extremely hard to show mercy so it is not a sword to fight with for fun. Whilst it is not impossible to show mercy when using this sword in a fight it takes a great act of willpower to successfully do so.
25-Sword of Fire
The Sword of Fire is very powerful in a low magic world and very weak in a high magic one as when it is activated it partly burns away with each use. (This idea was not mine but was borrowed from manfred.)
26-This Sword Uses You
When he lay dying a great king of old passed his sword down to his son, and unknown to anyone else, as soon as his son held the sword hilt he was possessed by the spirit of his father and forced to ride along as a helpless puppet in his own body. For centuries the sword ruled the kingdom and then the empire through the line of monarchs that it possessed until in one battle too many it's host was killed by a common soldier who sold the weapon to an antique shop owner without ever touching the hilt. For days the sword has laid there waiting to be picked up by somebody,anybody, that it can possess.
This sword is made out of enchanted ice and can cause frostbite with a hit, but even with a thick glove on it cannot be held for very long by it's owner or the owner will be harmed by his or her own sword. Also if the sword is taken into warm or hot weather the magic of the sword will fail and it will soon melt into a puddle of water.
This sword was enchanted to vibrate in the wound and therefore cause more damage, but the spell was messed up and it vibrates all the time so it can hardly be held and sends an uncomfortable judder down the user's arm. If put in a leather scabbard it cuts it, and if put in a metal scabbard it rattles noisily and annoyingly and can't be taken anywhere that quietness or silence is needed.
It shines as brightly as the sun, meaning no one including it's owner can look directly at it when it is drawn from the scabbard without being blinded on the spot. Whilst it keeps all creatures of shadow and the dark at bay when drawn, it's only real safe use is to light up an entire area when stuck in the ground. Only someone who is already blind will be able to fight with this sword.
A noble lady in love with one of the PCs has enchanted this sword with a love spell as a trap for him, and the spell will last until she either treats him badly, is caught cheating on him, or the blade of the sword is broken