Go to Dura Gra-Bols house in Balmora, by the riverfront. Go to the top floor and there should be some crates to your right. Search them until you find Gravewood Amulet (or something similar). What this amulet does is allows to summon skeletons without using Magica. Summon a skeleton, then kill it with whatever weapon you want. Repeat the process until the Amulet runs out of energy. Rest 24 hours to restore the Amulet and repeat until you are at 100 skill. Or use the cheat code.