Who thinks obsidian weapons are cool?

Obsidian color/texture, yes it's cool.

Obsidian as in the rock, not really only because it's not believable. Obsidian is like glass, and you can't really make a weapon out of it. I've seen images of knives and stuff but they are more for show than for use because the moment you use them it would flake or shatter. The only type of weapon you can make with obsidian rock is a club with obsidian shards embedded in the edge. It's called a macuahuitl, and it's more of a club type weapon than a slashing one. It's similar to Oni's Kanabo, or a baseball bat with nails in it.