Adding Heros to the game could be a good idea,example: You could have a Captain(Hero)with different boost to your Airshpi like shoot faster,improved commando time or this Hero could be a engineer implroving the using of coal.There could be a lot of roles that your Hero will play.
Commander, Engineering Corps
similar to the Heros in Endless Space and Endless Legend
i like it
I'd say do them a bit like so:
Each city produces one hero that can be hired. Each hero starts off with one skill that acts like the heraldry bonuses; as the hero gains experience through completed battles (in which their ship captures or destroys other ships, emplacements, etc.), they'll either unlock more skills at a rate of one per level, or simply improve upon the skill they already have.
Heroes can, of course, be killed during boarding actions (what good captain doesn't go down with their ship?), and should cost a pretty good sum of money given the buffs they'd provide.
It would be awesome