I think the OP was referring to dual-wielding, not to 2-handed weapons. Dual-wielding counts as the one-handed skill, so it will get decapitations. Glad to hear 2-handed weapons will as well

Exactly, so much news about decapitation is making my head spin! I've have long awaited a swift end to a TES battle where my enemies head slides off his shoulder and rolls down the hill.
Just think with decapitation confirmed and river-movement phsyics confirmed, we can cut the heads off our foes/townspeople/gaurds/Imperial Gaurds and send them down a river as a message to the next town that death is on their doorstep...