from what i remember it is possible to go over 100 (even though it doesnt show)
so putting fortify one-handed on top of a 100 one-handed skill set still is effective. dont quote me on that i could be wrong.
just save before you do your enchanting. then compare your one-handed weapon's stats before and after (the damage stat of the actual sword/dagger/mace whatever). it will change in real-time after u finish enchanting if it does anything.