Shield is basically the biggest outlier in his kit, how else would he be nerfed?
I like the nerfs they've done to the slow component of the kit (both the strength on Live and the duration on the PBE). I don't know how a 3s 70% AoE slow makes it out testing. Reverting the Q buff he got a few patches ago would be good as well. It's a high impact, high reward ability. Should have higher risk to missing it.
I'd rather see Riot nerf the base and scaling damage on the shield as opposed to nerfing the shield itself and push players more towards maxing Q first. Q max builds have a healthier ~50% win rate right now, and it's clear that's what Riot originally envisioned for him going by the champion videos, pre-release demos on Twitch, etc. If significantly nerfing the shield damage overly hurts him, then Riot would still have a path forward by increasing the damage on Q, further pushing players to Q max first builds (which would honestly be a blessing to everyone, more counterplay vs. Ivern, and Q max is a more enjoyable to way to play Ivern for the player too.)
I do think there's a decent chance that this nerf will end up pushing Q max builds for Ivern anyways, but...I mean...he's a support, right? He brings lots to the table outside of the shield but that shield is the most outright supportish element he has. A shield that taps out at 190 at rank makes it the weakest in the game. Well, tied with Karma but she can mantra her shield for additional strength. I guess if this ends up pushing Q max builds I count that as a win, I just don't necessarily think it's the right way to go about it, in so far as "fulfilling player fantasy" goes.
Also, there's the issue of itemization. He's the only jungler who's frequently building Redemption. It's OP as it is on true lane supports but the nature of Ivern's role on the team pumps that
overpoweredness even more. I'd like to see that item nerfed as well.