Yeah..so is his steel only 50%as durable? With IWs power, you're either invisible or you're not...... unless he's now 50% invisible.....so kinda see through, but not really?
Well, he was half of Colossus durability so I guess this applies to him being half invisible which wouldn't help him in any way tbh. Anyone controlling Mimic, I don't think they would even take that route of taking that ability from her since, well, they wouldn't even need it.
Well then there's Miss Martian. Does he get 50% of her intangibility? So he's...kinda intangible? Or only his left side? Top half? Can shapeshift, but only shapeshift into 50% of the things Miss Martian can? Diamond is diamond - against Emma, is his diamond form 50% as hard as a real diamond?
If against Captain Britain, whose powers are based on his confidence, does he need 2x as much confidence?
IOW, way too difficult to draw a line. Hence my vote out.
There's not a whole lot of precedent for powers like these, so I'm not sure we know with anything resembling certainty. For what it's worth, there are powers he almost certainly used at higher than a 50% capacity, but that's likely because writers just wanted particular power sets and didn't feel beholden to an exact representation of what 50% would be. If he copied a phaser in the comics, for instance, it's overwhelmingly likely he would be able to phase, with perhaps only the concentration needed or duration nerfed.
However, he can also stack similar or identical powers. He's done it a few times with things like fire projection and healing factor. So he could presumably end up with some full-strength powers depending on what templates he starts with and copies.