This needs tidying up.
At the moment, you can buy the same skill twice, wasting a hero skill point.
Also, one of them has an assassin elite that you can't actually buy.
Hero Skills NPC Dialogue
Nexus Icon
Vinraith
Yup, it's especially confusing if you've already got a lot of skills unlocked on your account for the class in question, as frequently every skill the trainer can teach is already in the hero's repetoire but there's nothing on the skill vendor screen to indicate this.