I think the text needs to be modified, since it seems you can't actually modify armour you're wearing or a weapon you are holding because of how the power works:
Interact to draw, retrieve, or swap an item, then add one of
the mods listed below to the item.
I assume that initial step is meant to be optional, but currently it's the thing that determines what item gets the mod applied to it.
This was my first reading, too. I sort'a think the intent is that the Interact is there so you can do it with that gizmo you stored in a 'Surprise!' sense but still letting you switch the polarity or reverse the magazine or whatever. Changing that to 'You may Interact [et al]. You may then add ... ' might help. Or might go over the word limit, what do I know.