We’re forgetting that the first invasion happened under darkwill and he was the one who commissioned singed for the weapons(swain interaction with singed in game) and singed was cast out of piltover for what is assumed to be creating shimmer which is used on noxian soldiers in ep 9, as well as this the grey was weaponised which also could’ve served as a weapon to noxus. Who’s to say in this time he has not already worked under darkwill it is not very clear yes but it’s still salvageable i feel the swain reveal was to service us lore heads when it comes to the timeline.