Enforcer's Axe (Greataxe). The charged M2 spins twice, proccing multiple posture breaks on bosses. Farm the Duke for this.
Go to Ministry . Get Frostdraw to 20. Farm the golems. You finally unlock Lumbering Slam . You can now kill a golem in 3 hits. Farm the Adret tribe for Meditation to swap mantras easily. best heavy weapon build deepwoken
Curved Blade of Winds (Halberd). It has extended range, a horizontal swing, and deals Slash damage, which few armors resist. Enforcer's Axe (Greataxe)
But claiming a heavy weapon is "the best" is nuanced. The "best" build depends on your goal: wiping a Chime of Conflict leaderboard, tanking a Diluvian Mechanism wave, or surviving a Voidwalker gank. Go to Ministry
The build's only counter is a with a gale pike who never stops running. But in a direct fight? You are the king of trades.