Coming from a discussion about Engineer, i have a suggestion to make. Its not a complete overhaul, but still a rather significant change which should result in a smoother handling of Engineer overall, in my opinion.
Build Pressure: Holding reload with the Steam-Assisted Crank Gun (Mk III) equipped builds Pressure. Each stack of Pressure gradually restores the Ability Bar. Stacks up to 5 times. Pressure is lost when the Ability Bar limit is reached and when firing the Crank Gun.
Reloading the Crank Gun is an unneeded minigame in a possible stressful environment on legend, even when we currently use the talent to not lose pressure. But the talent makes the handling at least somewhat workable, so now its the standard. Of course this would need a change in level 20 talents, but i have “simple” solution for that too.
Full Head of Steam: Bardin gains 5% Power for each stack of pressure. Pressure is lost after 10-15 seconds.
With this talent, we have the original passive ability back, but with an upside. 25% should be significant enough to consider this talent. Not sure about the time, thats a balance situation i cant say anything about.
Experimental Steam Capacitators: Reaching 5 Stacks of Pressure gains double the Ability Bar restoration speed.
The original talent would obviously be way too strong with the new passive, so i guess a talent for basically just cooldown reduction would fit. Obviously Fatshark has to balance out the numbers properly, because i am not sure if double the speed would be already too much.
Superior Gaskets: Each stack of Pressure grants 2.5% Attack Speed. Max stacks reduced by 1.
Still the same talent, just without the no pressure lost part, since its now in the passive.
That would be my suggestion. I think its a fairly reasonable change.