they could add no extra force. What would it push? what would it pull? When you punch you extend your arm and put some amount of your body weight is behind it. if it made your punches faster, it would have to be pushing on something. However, that would mean it is using your spine as a leaver to pull your opposite shoulder back, which would produce a crazy torque on your spine, and prevent you from putting your weight behind the punch as now it is a motion separate from your kinetic chain. In that case the punch would be weaker if harder to block. Which is not worth turning your spine into a slip'n'slide. As newton's laws meaning all that force would act back on you as well. if the gear was a full exo skleton that could touch the ground then it could work. we don't see those though.

Technically the boxing gloves are small shields you use to protect your face with. So they do get that armor part right.

If the metal goes over your hands it becomes like brass knuckles. in that sense the gear become like knife frightening. Where the point of gear is to block the strike that would otherwise cut flesh and bone. In that case there would be no use for the power unit. We saw a shitkicker use them like that. However his gear has dynamos on them. The little jet engines spun up to make the punch.... stronger? However, having a turbine on your shoulders would gyro stabilize them. meaning he would be even less likely to be able to throw a power punch.

OG Roman boxing was like that, they worse cestus, big leather and metal boxing gloves/ brass knuckles. So, one punch could break a skull, so you had to be very careful about blocking he metal bits with your metal bits. it was a delicate dance very much like fencing. Not like boxing as we think of it at all really.