Are you talking about skills that a hero can learn?
If so then you can definitely disable the ability for the player. I am not a 100% sure if there is another way, but testing should be quick and simple.
Finally finding about some of the bots that are flooding the users online - bytespider apparently is a huge offender here - ignores robots.txt and comes in from a ton of different IPs
Ghan has said he has fixed this. Monovertex please confirm this fix. This was only a problem with people that had signatures in the upper levels like not the special members but the respected members.