Board Thread:Speculation House/@comment-27092449-20151018200124/@comment-25479664-20151109140343

In reality, obsidian swords would be extremely brittle. The only kind of obsidian weapon in real life with any sort of significant durability (w/o metal reinforcement) are obsidian knives, due to them being very short and not taking too much strain on their brittle molecular composition. Then again, RWBY isn't exactly known for realism, so there is that.