Ways to increase physical dmg on Brutalus:
Elixir of Demonslaying'
Adamantite Sharpening Stones or similir,shammy frostbrand weapons.
Survival Hunter with Expose Weakness talent.
More warriors for more Sunder Armor(roge`s Expose Armor doesn`t stack with it so don`t use it).
Rogues stacking Hemmorhage.
Minions-both normal and spell/talent ones.
Druid Faerie Fire.
i`m probably missing more so comment and add...