Even a 'bog standard bloke' Space Marine is a terrifying engine of genetic engineering, equipment and training. End of the day, that tactical marine is a scary piece of work in all aspects.

I prefer to go the route of 'work with what you have and make that awesome' here. I also want to leave room for cool kit and things to happen, instead of having characters start out with an Arsenal of Awesome already. 

I mean, the Blackshields are pretty much centered around Marines in armor they struggle to maintain with looted equipment that they also struggle to maintain. I want to hold true to that. Also, these characters should, in a sense, be able to carry on a fight with their fists and guile, and I think that needs to be kept in mind as well. Every bolt loosed, every canister of promethium, every grenade thrown is an expenditure of limited supplies. They will have to think flexibly and fight smart.