Weren't the Jedis actual wizards, and others were forbidden from wielding that weapon exactly because someone would get maimed? The weapon is tech but the reason they don't damage themselves is clearly spelled out magic.
Well, Luke wasn't a Jedi when he was first handling it, and Obi Wan didn't seem to mind at all giving such a dangerous object to a completely untrained person. Hell, he didn't even tell him which side to point away from himself.
