Champion Spawn Artifacts lists the new drops for champions

From UOGuide

The Butcher's War Cleaver is a craftable Two-Handed Weapon made by Blacksmiths. Like the Bovine Slayer Talisman, it inflicts double damage on Bulls, Cows, and Gamans. Unlike the Bovine Slayer Talisman, it is not effective against Minotaurs.

Name	Ingredients	Fixed Stats	Recipe Obtained From
Butcher's War Cleaver	18 Ingots 1 Turquoise	Bovine Slayer When used on a leather-bearing corpse, this Cleaver skin the hides, convert them into leather and place them directly into your backpack.	Smith Quests. Rare.