I'm just reading up on him for an upcoming debate. Exar Kun doesn't have many TK feats but killing Odan-Urr with it should be fairly substantial.
I'm going to go and look for the source that notes he severed Dark Jedi from the Force. The fact alone he could affect Exar with TK and taught Sever Force to Nomi, who ended up using it successfully, makes him pretty powerful IMO. As well as his ability to telepathically communicate with thousands of Jedi at the same time and utilise Battle Mediation to great effect.