If it has a number of uses, it can be activated. I’ve never seen a “natural” artifact that had any wielded functions, only carried and activated.
A lot of the passive (carried) abilities will give you a hint of some kind. There are stat modifiers (good ones are positive, bad ones are negative, of course), and they tell you when you pick it up. “You feel hungry” means it has a bad ability that drains hunger (not by a lot, but it’s there). Same with thirst. “You feel a prickle of insanity” gives you occasional hallucinations. There’s a message about one that makes you occasionally emit a loud noise when you walk, one that occasionally teleports you (that’s considered bad, but it can be useful sometimes), one that irradiates you, one that gives you “otherworldly attention”, etc.
The most of the good passives are pretty obvious. The active ones… well, activate it and see what happens! Some of the good actives are a little bit hard to notice, though (if you aren’t in a condition where it’s useful - there’s light, for instance, which is not so obvious in the day).
The one that covers the area around you in blood is on the “good” list for some reason. I mean, it’s not “bad”, I guess, just entirely useless.
