Support is actually miserable right now. It's literally who can buy ardent first, ignoring all wards / boots/ item upgrades / etc. Who the fuck honestly has fun playing like that? The answer is nobody. Anyone who says otherwise doesn't actually find the playstyle fun, but instead finds the fact that you completely fuck over your enemies in lane by buying one item and pressing 1 button fun. There needs to be, as people put it, skill expression in the item when there is none
As for the other items, they really aren't in a bad spot. Knights vow sounds strong, and it's a good item, but it isn't as strong as people think, and the damage isn't lost all together, it's just redirected onto a new target as true damage. Locket actually requires a player to time it, since it has a very short duration, and decays rapidly. If you want maximum effect, you need to use it at opportune times, not whenever. This is how shields are supposed to be. They're supposed to be opportunistic damage shields, not per-emptive at all times damage shields.