The approach of humanizing weapons is an established Japanese method of enhancing the story, and in days long past to hold that a sword was alive and that the sword had a soul was a means of making the combination of the swordsman and sword a supernatural combination.
Upotte!! tried this approach, but somehow managed to link "military assault rifles" to young female teens. I had quite a bit of trouble with cute kids being deadly, and having been created as teens, never to age or change, just to be replaced, and the story simply did not make sense. That there was a deliberate sexual aspect assigned that flew in opposition to the independent aspect of behavior and the training, and it sometimes seemed like it was trying to parody the genre.
Those were stumbling blocks, but the huge stumbling block was the description and statements made about the weapons. Most of the information seemed to be copy and paste from sales brochures, and most of it was incorrect. Not somewhat incorrect, not a few tiny errors, but so wrong it boggled the mind.
A story that did not make sense layered onto incorrect basis of character construction is not likely to produce a strong series. It was interesting in the same way that a train wreck is interesting, and the less you know about human motivations, the weapons in question, and about warfare the more likely you are to be able to enjoy it.
It does have pretty good music, and there really is nothing like it, so it stands alone in its field. You may enjoy watching it in the same way that a deliberate train wreck was staged for audiences a bit over a hundred years ago, but at the end, it was still somehow lacking, at least to me.
Good luck with it.