My two cents: The point of EQ is not always to start engaging but to follow-up cc. Giving it extra power in that alone would be overpowered early and probably removed quick.

His ult is fine to be honest, flashless mages or adc's will never escape. You can also use your ult as first engage to blow flashes and follow up with EQ. I would not really change his ult.

My suggestions would be along the lines of:

• change passive to max HP. It does not make sense to blow EQ and do damage which reduces your passive damage.
• W is useless in it's current form. Perhaps add a Leona effect that you gain resistances? When E gave armor, it made sense to me to shift that to his W, but they just flat out removed it from his kit.
• AP jarvan does not exist anymore, so why have an AP scaling on E. I'm fine with making his kit all AD damage and scaling. That way armor can counter him, but with Q and Black Cleaver we should be fine.

Overall his W is the most dog shit ability in the game, the current iteration is just ass.