Hello everyone! So, I have been on Scadrial for a while and I was wondering why obsidian knives? Do they just look cool? Why couldn't Vin or anyother Mistborn use say a turquoise knife or any other non metallic knife? Does obsidian affect Allomancers especially? Or is obsidian a stone blade that is exceptionally strong and not brittle/won't snap under pressure? Maybe I'm over analyzing things, but obsidian seems to be mentioned specifically in regards to Mistborn weaponry and some soldiers I thought had obsidian tipped spears? Thanks everyone!