I like them. Except combine them, call it Countermeasures, and let someone activate as many as they'd like. They would still expire within a week, though, so you'd have to decide if you wanted 10 active counter-measures, and MAYBE have some for next week, or only use a couple, and save 'em up.
Countermeasures
Has a chance to nullify the effects of an offensive artifact. (offensive artifacts being the ones labeled 'enemy ship'

)
I'm pretty sure this wouldn't break the game at all, as there are likely to be more offensive artifacts than traps in play at any given time. Plus, maybe there wouldn't be a huge surplus of certain artifacts if you had to shoot 5 missiles at someone instead of just one.