Having your strongest axedorf getting attached to a copper axe and a copper shield is very tough if you're going to get at least iron ones soon (is there a way to turn that off?)
Copper shields are the best you can make at the moment. Heavy copper has a better chance of stoving a skull in than light leather (which can happen). I,m not too sure how copper shields and dragonfire will interact in the next version, or whether density will be less of a god-stat for blunt weapons, or whether attacks will become capable of going through shields the way they can go through armour, but for now copper is a great shield material.
Attachment can be overcome by forcing the dwarf to drop that particular piece of equipment. The best way, I think, is to order them to equip a specific shield and then melt down the one they're attached to. Forbidding might also work. I've seen forbidden items in dwarves' equipment screens (usually single bolts), but I'm not 100% sure if they were forbidden when claimed or if they became forbidden at some point and weren't removed. The latter is far more likely.
Named weapons and shields are far more annoying because, while they can be destroyed, they will forever haunt your stocks and artifacts screens.