I'm an unusual mercenary. Some call me a Ninja, but that's one of many labels. I don't charge by the day, You can just buy me once. I have no legs so you need To bring me your victims And drop them into my knives. I'll keep cutting and slashing until you tell me to stop. Pour out the remains into your glass. Yummy!

None save Lestat, et al., can escape me.

A tool for opening crates and yet also a powerful weapon to fend of some pirates

I tend to be a wild card I might make you laugh very hard My archival wears a disguise Sometimes he’s a man but Sometimes he flies

Common in sports, it’s usually round. You can kick it and throw it or toss it around. They make ones for stress that you can squeeze. And another word for a certain kind is testes.