Moon Knight needs to be reworked, not buffed/nerfed. Here's my rework:
Since the release of this game, Moon Knight has been a hot topic of discussion for many reasons: his poor characterization, his skill-expression, and his viability.
It's gotten to the point where the Devs clearly don't know what to do with him. Upon release it was clear some aspects of his kit were "broken" (specifically his ultimate). Over the span of the game, Moon Knight has received buff after nerf after buff. Until where we are now, where Moon Knight is in a sorry state. Last season he had the lowest winrate in the game across all ranks and was at least a bottom 3 win rate in each rank separately. The recent buffs haven't done much and it's clear that he's in a bit of a sorry state.
The problem with Moon Knight comes down to the following things:
Skill level - many players feel like Moon Knight in the past has been too easy to get value on for such little effort - particularly in lower ranks. Higher ranks argued that he required more skill in those ranks to get value (holding down m1 wasn't enough), although he was mainly used for combining his ultimate with Groot.
Strong in low ranks, weak in high ranks - similar to Black Panther, Moon Knight is a feast or famine character that relies on poor positioning and poor team cohesion. A poorly coordinated team suffers against Moon Knight because of his shear damage output and his ability to get picks on players out of position away from their team. In high ranks, the chances of this happening gets slimmer and slimmer as players improve positioning and teamwork, making the character less and less viable. Buffing his numbers would simply result in him being overkill in lower ranks.
Ult-Merchant - Moon Knight used to be a strong pick due to his ultimate which was easy to obtain. The ultimate in itself isn't great, especially if not paired with another ultimate (like Groot's ult). Since the ult-charge nerf, Moon Knight isn't picked for that reason anymore so has much less of a niche. He's okay for spawn break but there are other characters who can do that equally as well, if not better.
Moon Knight at the moment is simply stuck in a vicious circle of being too strong or too weak. So here's my suggestion:
Rework him into a Vanguard.
I have been a Moon Knight fan for almost 10 years. I have collected over 200 Moon Knight comics and read all of his runs (I am a massive Marvel nerd). He's my favourite character and when I heard Marvel was making a hero shooter (at the time I was playing Overwatch - begrudgingly), I couldn't wait to play my boy in a videogame again. Now, when he was announced, I was surprised to hear he was a DPS. Whilst yes, he can indeed fit that role, Moon Knight to me was much more of a Vanguard.
In the comics (and later in the TV show), Moon Knight has had very high durability and his "insane" characterisation resulted in him having a rather unusual fighting style: Moon Knight doesn't block incoming attacks. Instead he tanks them. He takes the hit in order to open his enemies up for a counter-attack and to throw them off guard. If that doesn't sound like a Vanguard, I don't know what is. In the TV show he was also shown to block (and send back) incoming bullets through the use of his cloak (not very comic accurate but can definitely work). He's also a melee fighter, NOT the "random bullsh*t go" meme character (that panel isn't real btw).
I have 150 hours on the character and he was my first Lord and my first Champion. If I was to rework him, I'd make him a Vanguard with some sort of damage resistance ability, a block with his cape, and give him some sort of melee attacks that perhaps give him slight overhealth or increased healing intake (just to make him more tanky). Of course increase his hitbox slightly. As for his ultimate, you could keep it the same as it is a decent zoning ultimate (making space being a Vanguards main focus), but it could also be changed. I'm open to suggestions.
Thank you for coming to my TED talk.
TL;DR: Make Moon Knight a Vanguard. He fits the role better, would fix his poor balance state, and add to the lacking Vanguard role.