"They also used a type of bow or crossbow that the warriors of Horus wrote off as decorative parade weapons, until a skirmish revealed that they could emit bolts of light fully capable of punching through Space Marine armor." -Lexicanum
"It should be noted that the Interex warriors were quite a match for the Space Marines under Horus' Command." -Lexicanum
They were a match for the Space Marines, thats a plus, even under Horus, "the most powerful among the Primarchs", "a tactical genius. He knew precisely which force to send and where to send it, showing no mercy" -Lexicanum, thats like another 3 plus' then times that by like 5
So you must be thinking like those guys thinking its just a little pussy weapon right before it goes through your "near indestructible armor" and your dead
I GET IT I GET IT. But the adeptus mechanicus wouldent. The second they find out about this, the whole chapter is dead.