Or just remove the weapon from his rotation until level 6+. It feels too strong, even when put against level 10 weapons (A few dropped off the boss, one even purple. This level 6 Axe just crushed their stats.) Braccus's Spear was slightly better than other level 3-4 spears. So why is this SO STRONG?
Do you have example stats on the level 10 weapons that Sundering Cleaver crushed?
Sundering Cleaver has 108 average damage, +2 Str, +1 warfare, and Overpower (this is the best part.)
In my game I have an epic level 9 axe that does 162.5 average damage, +4 attribute, 10% extra critical damage, +1 to 2-handed, and grants Whirlwind.
Heck, a level 7 white, crafted mace does 126 average damage, and can be crafted by anyone with Tongs+Cloth Scraps. Aside from the Overpower bonus, this is better.
Sundering Cleaver is good, but It's mostly just so good at and before level 6. If you're just getting this axe at level 6, it's very cool, but good level 7 blue items outperform it.