So I had been thinking of what would be a good fit for the third tier of Warchanter and this is the idea i came up with.
Bard Warchanter 3
usage passive
cost 2 ap
Requires Bard inspired attack 3, bard inspired damage 3
Your studies into war have allowed you to realize your maximum potential. You receive an additional +2 to your intimidate skill for a total of 6. You gain an additional 10 hit points, heavy armor proficiency (and the ability to cast arcane spells in heavy armor without arcane spell failure) and your base attack bonus is now the same as a fighter of your level.
So basically at 20th level a warchanter has a base attack bonus of 20. Part of the reason behind this is i would like to see the warchanter get something that benefits them and them alone, from their PRE.