I do agree that guns are a bit more complex. Given the large amount of guns added by the gunner update and the very slow change in PvE metagame towards powerhouse guns (Magnuses, Autoguns), I feel like most people would make poor ratings. Nevertheless, I don't wanna delay it more than necessary so let's get things out of the way.
The only thing I feel like we should change from the current model is perhaps the amount of required guns. Given that there are a lot of plain reskins now (Blasters, Gilded Griffin, Grim Repeater; not counting Winter Grave because it's quite different), maybe we should exclude those from the amount of guns required to vote. That is, if there are 31 guns in total, the amount of guns required to vote would be 10 or 11 using the current model but it might be fair to exclude the plain reskins introduced in the gunner update making the total amount of guns something like 25 and the required amount to vote 8 or 9.
Of course, we'd still be rating the reskins.
Bombs should be more important. If the devs are still developing this game (I think they are but Rise of Knights and..) then they could use your data to possibly tweak the bomber/swordy update that probably doesn't exist and is just speculation.