Shoc properties... they're more random and extreme than the CS/CoP counterparts which are boring almost... I'd imagine mysterious objects with other-worldly effects to be somewhat... unpredictable
One thing I always thought artifacts should have are variable stats. I.e:
(Using CoP attributes for a Jellyfish)
'Low' Jellyfish: -.5-1% rad > "Stalker, can you bring me a few Jellyfish I need for an experiment? Less volatile specimens would be favourable."
'Mid' Jellyfish: -1.5-2% rad
'High' Jellyfish: -3-4% rad
'Perfect' Jellyfish: -6% rad > "Hey man I'm after one of those artifacts they call Jellyfish. Only the best quality will do. You'll be greatly rewarded!"
Obviously the lower spectrum of the artifacts will be far more common than their perfect versions, necessitating a players patience in hunting them. Another example:
(Using CoP attributes for a Mama's beads)
'Low' Beads: +1-2% woundheal | -<.5-1% rad
'Mid' Beads: +2-3% woundheal | -1-1.5% rad
'High' Beads: +4-6% woundheal | -2-3% rad
'Perf' Beads: +10% woundheal | -3-5% rad
Even the perfect category could have variables, making the most favourable versions, like a +10/-3 beads even rarer.
Just a thought