Toady, I don't think you need to worry about non-lethal weapons just yet, because I assume that the most lethal object in most Dwarven barfights will be a Pick stool or chair. (Which could actually be pretty lethal if it's made of stone or metal ).
Oh wow, there's something to really consider. Furniture items are pretty stuck where they're placed. (With few means for them to be moved around/destroyed without player direction). That could be a hairy problem to solve. Dorfs should be able to arrange the bar/inn furniture objects to their initial placement. But what would dorf do if a furniture object is broken during a bar/inn fight? Telegraphing that info to player may be tricky. But that could be a pretty interesting frame work. Dorfs being able to arrange the furniture on their own. Setting up barricades? There might be other nifty applications.
Somewhat bizarre (but IMO oddly workable) thought: use a modification of the "Pasture" function to handle furniture in certain rooms, such as a bar, etc. As long as the furniture is inside the room, it's OK to be moved around by whatever means. If it ends up outside the room, a job gets generated for a furniture hauler to move it back inside.
Interesting idea, but you could end up with stone thrones moved away from tables in dining room, or cabinets blocking the exit in rooms if you only consider getting the furniture back in. This could probably be handled better through a job similar to cleaning, with a low priority except when it's out of the room, and as high as the lowest order requiring use of that object.
But anyway this requires fighting against the current framework right now. Rooms are made from these objects, around these objects and assume that they are fixed.
For all we know, a built throne could even be a totally different object than a being-carried-throne, rendering the idea non-trivial to say the least.
Let's hear what Toady has to say about it first.