Key Axe
If you completed .hack Part 1: Infection and finished the OVA Keyword dungeons you should have an Ice Bar. If not, go to Delta: Hideous, Organ Market, Scaffold, and when you reach the Statue of Gott you will receive the Ice Bar. Go to the Root Town and look for a player named Panta. You trade the Ice Bar to him for a Level 38 Key Axe.