Upon initial examination, this bow does appears to be much like other bows made of light colored wood, if a bit yellow with age. Once someone picks it up, though, they will quickly find that it is not wood at all. It’s weight is slightly greater then that of a normal bow, and the surface has the cool, porous feel of the bone it was made from. If they pull back the string, an arrow will immediately knock itself. The arrows are rather standard, with wooden shafts, though the head is made from bone chips. Upon loosing the arrow, the string will spring back, clearly ringing with the sound of a harp.
There is a history to this bow, though it is not known by many. It was created by a bard who’s name has been lost to time. He was working with a group of adventurers on a quest to rid a swamp of trolls. During the battle, a troll came too close so he was forced to use his bow to beat it back. Unfortunately, this cracked it beyond repair. He was able to cut and shape the bones of the troll (which was slain when Jarret came to his defence and hacked it’s head off from behind) and strung his new bow with all he had available: The strings from his harp. Sigrin, the party mage, then used his considerable magical crafting power to enchant the bow.
Strength +1 (Makes the player slightly stronger while using the bow)
Regenerating (i.e. unlimited) arrows (They were just standard for mine, but they can be magical arrows.)
Intelligence -1 (The player will be slightly less quick witted while using the bow, and have a small amount more difficulty figuring out problems.)
Any of these properties can easily be altered or changed to suit your game. The only thing I would suggest is that you keep the properties and penalties in line with what a troll would have/give.