You need spell check:
Upon their arrival they found Bonuman and his men...waiting to meat them
.
The above sounds a very renegade thing to do.
Anyway.
its a start but I cannot get into the fluff, the reasons for the change seem pithy and an afterthought to what you wanted to achieve, which I suspect is to allow marines greater access to heavy weapons and access to
IG like equipment?
The reason for the mechmarines turning traitor needs to be fully fleshed out before i can believe in this.
Also
Mechmarine terminators:
2 Thunder hammers or power fists? I have heard of redundancy but why this configuration?
Why does Aximand get warp powered hoojits and the daemon prince gets *new technological device* name. For dark mechs their weapon names sure are sterile.