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Digging a slug out of an arm and stitching it back up is a process that I'm sure, for the humans, would take a couple of minutes. In a universe where we have teleportation, faster than light travel for giant space ships, super soldiers, and energy weapons, I'm pretty sure the technological masters that long surpassed all of these scientific marvels can achieve this in seconds.
Also, like espraile said, you're just making a much bigger problem by hacking off the arm below the wound.