Bullying in all forms can have devastating consequences.
You say warnings, from the game, or your clan?
Sometimes the best way to deal with a situation is to ignore it, because if its done for attention and there is no response,theres no feed back,no reward.
If the harasser is an invidual player, though potentially risky, you could offer an olive branch, and offer membership,
was a few like this in my old kingdom... i call them terrorist...
What have happen is that clan have unite and he was always with bad repute from pop, always zeroed when he was fropping shield, never accepted in any clan, etc... after a time, they have quit the game...
In my new kingdom, there was one like this too... have not stay long and he have chose to immigrate to a other kingdom with drakar...