The prices to raise skill caps are different between the two trainers (IIRC Hermosa is a little cheaper with warrior skills, while Kenneth is cheaper with mage skills). That isn't much of a practical difference, though, since by the time you get the battle tower you should have plenty of gold, and can easily farm more with your runners (sending them for diamonds and malachite ore to sell).
Talking to Kenneth on the beach when you start off on Sentinel Island, he can ask you to issue a challenge of a duel to the death to the other trainer. If you agree to this and pass the message on, Hermosa will agree. Kenneth will try to back out when he finds out the other trainer is a woman (if you tell him earlier he will not propose the duel), but if you insist on the fight taking place, Hermosa will win.
