I feel like they should be for weapons, but I have a stack of 4 lesser chernobog runestones that do 2% attack power and they will not slot into weapon slots, just says I can't fit the upgrade. But when I open up an armor slot like boots it will slot in there.I'm pretty sure they are for weapons, at least mine are. Maybe your runestone is bugged?
They go on weapons for me. However, they still seem to be bugged as sheet dps doesn't improve with them slotted.
yeah I googled the crap out of ot and could only come up with the bug where they don't actually work...but I cant find anything about them slotting into armor only, and I'm 100% sure. Im kn ps4 and the new parch hit today, dunno if that messed it up.They go on weapons for me. However, they still seem to be bugged as sheet dps doesn't improve with them slotted.
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I found a video here http://youtu.be/mreR2Iy5eXE where a guy gets a greater one and at the very end when he clicks on it only his armor highlights...
On Pc i can slot them just fine into my weapons. Hmm so looks like this is system specific. THe runes work on pc sheet dps ONLY gets updated when you pull out the weapon as the Attack power of the runes is weapon specific. SO check your stats before and after a weapon is drawn and you shall see that the corresponding weapons stats have been updated.