Nothing allows a Powerfist, Chain Fist, Thunder Hammer, Power Claw, etc to strike faster then Initative 1, unless the specific warrgear has a special rule itself, like Daemonhammers have.Powerfists, however, are difficult and cumbersome to use, so attacks with a powerfist are always delivered at Initiative 1 (ignore Initiative bonuses from special rules, wargear, etc).