Unarmed is a crippler imo. At least, i can -in theory- cripple both legs or arms in one turn, but to be fair, other characters can do that too...
Only problem is, that if youre against a char with high endurance(pvp), theres only a small chance to cripple...
http://falloutmods.wikia.com/wiki/Critical_hit_tablesThe parts with "Roll EN or get 'effect'"
Secondary attacks should have an effect that lowers EN of the enemy. Like certain item perks reduce AC, or DR... They cost even more AP then aimed sniper shots, and tbh, i dont see any benefits to use them, because i can just try to cripple twice with haymaker in a turn.
The armor piercing effect is useless, because:
Piercing Kick
Requirements: Unarmed 125%, Agility 8, Strength 6, Level 15
Damage: +12, armor piercing
AP: 9
Critical Chance: +50%
With the bonus of aimed shot+50%, you will score a guarenteed crit every time afaik, and most critical effects bypass armor anyway, and doesnt need an EN or LK roll to get the effect.
If piercing strikes could have an increased crippling chance(with the help of reduced EN) i would surely use it more often. My 2 cents