HtH Evade/Fallout Tactics
In other words, with 3 unused AP and 120% skill, the player character receives not +3 to AC, but +36 (+2 base and +10 from skill per AP).
The perk only takes effect when both item slots are considered empty by the game. The game considers them both empty if the items equipped only use unarmed animation frames. In other words, HtH Evade applies not just to completely unarmed attacks, but also knuckles, power fists, and grenades.