I feel your frustration, I have had my share of battles that went on way too long (or jaw-droppingly short) because of some talisman effect that I did not anticipate. But I get the feeling that a talisman disable effect would make things so much worse without strict limitations - maybe if it were like the Skill talismans (Death Mark, Meteor, etc...) where you could only use it if you had enough power points. I don't know...

I agree with HK-47 that a better idea would be to have arena seasons each week. The possibilities would be endless (no Assassin characters, no Shields, all stats lowered by 50%, only Magic damage characters, all characters afflicted with Heal Block...).

Seeing the same characters and talismans over and over has made the arena quite predictable (and somewhat pointless), and this kind of feature would encourage players to dust off characters that don't see much action and would most certainly make the arena an interesting place again.