Are there any games that provide some characters with the option of playing as a weapon, possibly wielded by other players?
I've never heard of or seen a game that has any rules or specific about this and I was thinking that it would be a really interesting thing to play as a magical weapon with it's own character a traits just like a normal character but someone else that you're playing with can use your character as a weapon
Wield promises exactly this. Its Kickstarter just completed, so it is only out in playtest form at the moment.
A Fantasy Roleplaying Game where you play an ancient, powerful weapon and the heroes you wield are disposable hit points.
Wield is about power. How much do you have, how much do you give up and who has power over you? It is about negotiation and compromise, surrendering and gaining power over another.
A vatcha has almost limitless power, but it can only channel that power through a wielder. Thus, a compromise must be made between the two. How much power will the vatcha surrender and how much of his own Destiny will the wielder compromise for the vatcha's goals?
BloodLust
This game is based on that very concept. The players are encouraged to create god-weapons and be wielded by other players. This game is highly inspired from Michael Moorcock's Elric book serie, therefore a strong part of the game is centered on the relation weapon-wielder, and as the weapon satisfy its lust (not necessarily for blood) through the wielder, it gains power but also some control over the wielder.
I'm not sure there is an english translation (the game is french and was apparently translated in german), but the very concept if not the game mechanics are depicted on wikipedia, and probably somewhere else. If you are not afraid of tweaking rules, I once did that to the fantasy game I use to play and it was a very interesting game session... If you speak french, you can find more about the game here.
Alternatively, I'm pretty sure you can find official/homemade rules to play magical weapons in Strombringer, since the universe (Michael Moorcock's) features some magical weapons with some conscious.
I have done this sort of thing in both D&D 3.5 and in Legend.
It’s very awkward; the item has to be treated as a Tiny Construct or something, and all the particulars have to be detailed. Balance there is very tricky. The closest thing to useful information, the intelligent item rules, don’t really work very well for a player-character.
We wound up with something like a Tiny Construct with a Perfect Flight speed, scaling magical properties on the weapon if they were swung (or that they could use as a “natural” weapon), similar to the soulknife’s mind blade and mind blade enhancement features, though scaling with HD and not as restricted. The character wound up with very few HP, causing him to die very suddenly and anticlimactically after being caught in the edge of a fireball that was primarily aimed at someone else. It’s not an easy thing to do.
Legend’s official rules do not cover this.
However, the homebrew Ego Check feat was made by one of the developers, and has been used in many successful games, including one I have been in. Because Legend is a little looser about a lot of details, and has more consistency between Types, you can easily just be a Small Construct and it will work fine (Constructs neither automatically get a smorgasbord of immunities nor lose out on a lot of HP).
Charnel Gods (a Sorcerer Supplement)
There is a supplement to Sorcerer called Charnel Gods that fits to a degree. In Sorcerer every character is a sorcerer with the ability to control demons, however demons are defined in each setting differently. Sorcerers risk losing their humanity due to this and when their humanity hits zero they become NPCs.
Charnel Gods defines demons as great weapons created by the gods (think Stormbringer) to be wielded by heroes defending the universe from those who would destroy it. The basic scenario is a late period in the world where it is nearing destruction similar to the end of the Elric saga. Each character wields his demon weapon defending the world until someone hits zero humanity. That player then describes how the world ends and how the great weapons save the universe. The DM then creates a new setting at the end of the world period. The players create new characters who wield the same weapons. Thus, while the weapons technically aren't the PCs they are the player continuity over time.
The creator of Charnel Gods was out of the loop for a while but I have found a link on story-games that might help. I know Ron Edwards is still selling Sorcerer. It really is a fun setting and I think might fit your needs. Seeing players think like Stormbringer as they work to dominate their own characters (and even say the "I was far more evil than you" line when their character hits zero humanity) is a unique experience.
