This idea is that in the weapons skins part it could appear an option than when you are in gamemode like warzone and when you pick a weapon of a enemy its automatically change the colour weapon to your old weapon skin for example : You kill someone with a light rifle, and the enemy you kill have the DMR and you too have the DMR, and the enemy dmr have and different skin than the one that you have, so it changes to your skin, its understand? I hope you understan 
goodbie my gamertag is “Ram Tsubasa” good luck in Halo Wars 2, I follow you serie from Halo : CE and its awesome how it grows 
good luck with the next Halo’s upcoming, goodbie, LIVE HALO!!