I'm pretty sure it's doesn't. From what I can tell the number representing a skill's level seems to primarily determine what perks you're allowed to pick from that category in Skyrim, unlike previous Elder Scroll games. Since at 100 you can pick any from that category there isn't really any point of going over that.
The skill level doesn't do anything except act as a perk restriction. In your case, in order to increase 1-handed damage, you need to get the perk that does it.