As it is, the constitution stat is not that great. Every level, if you chose it, you can get 3hp. But every level you do is a level you do not increase intelligence/essence/strength. I have often ended up mid-game with my heroes lv5+ and still at 10hp, which is rather low when fighting against an army that can hit 80's. My idea was to have your heroes' health increase every level, with the rate that it increases effected by their constitution.
Something like this:
Instead of: Con = HP
Have: Con + (Con/5)*level = HP
That way even if they keep the basic 10 constitution, they will at least get 2hp every level. But if they upgrade it they can get 3 or 4hp every level along with an increased base health. This way they won't die as easily and will be much more useful mid-late game.
