onslaught has kind of been retconned anyway. saying he was afraid of the juggernaut which is why he targeted him first.
and also the power was meant for xavier, and it somehow interrupted the power flow to cain? hey, i'm no expert but thats how i took it.
edit: back to the original topic. i dont think herc is as strong as juggernaut... at all. so juggernaut FTW!!!