Is Swain Too Weak?

I'm not the best Swain player, or the best League player by any means, but I can't help but feel that Swain is a tad bit under powered. Most of it stems from his ultimate I feel, which looks like it would be something that is already hard to balance. I feel like trading off explosion damage from Demon Flare into an increased health drain would benefit him more. On the Swain Mains subreddit people have brought this up quite a bit. One idea I remember seeing is removing his Demon Flare entirely, instead giving Demonic Ascension increased drain over time, and a lower CDR on other abilities so that he doesn't just pose at you until he can cast Demon Flare. Another I remember seeing was removing his shards entirely and then giving him permanent health and/or MR/Armor based on his CC passive. Again, I'm asking this moreso as a question aimed at people with more Swain experience than me, as I really don't know how to gauge characters too much themselves in terms of power.