You get a bonus to hit with unarmed attacks.
This bonus is an adept bonus.
If you have more than one adept bonus which applies to the same roll, use the best one.

Attack twice with a wielded weapon, or twice with each dual wielded weapon.
(Unarmed counts as a weapon)

Make one unarmed attack, which deals double damage* if you hit.

*Do not double
ongoing damage, or
damage boosts which only apply to one hit, and cost resources or have limited uses
(Wrath, Arcane Flare, Venom Strike, Mortal Blow, Overpower, certain Poison Vials).

To double a damage die, double the number of dice (instead of doubling what the die rolls).

(ex: If your unarmed attack normally deals 1d4+2 damage, a Heavy Attack would deal 2d4+4 damage)
(ex: If your unarmed attack normally deals 1d4 +2 damage, a Heavy Attack critical hit would deal 4d4 +4 damage)

Clarification:
Do double any “extra damage on a critical hit”,
but not the dice doubling effect of a critical hit.
(A normal critical hit will be affected by the extra damage dice.)
(Critical specialists deal extra damage with critical hits, and that boost should be magnified).