How many matches into this are we and people are still making the same mistakes regarding Arthas.
1. This isn't Arthas as the Lich King. This is DK Arthas. The Lich King is Arthas + Ner'zhul anyways, not just Arthas.
2. Frostmourne doesn't kill or rend souls on hit; See: Illidan. It captures souls with the killing blow.