There are all kinds of mutually exclusive edges that enhance martial trance. How about one that adds some ticks to the duration? Make the exact number wisdom dependent, similar to how Kuma Buki gives variable hp boost depending on wisdom - I'd consider it worth taking if it added 3 ticks, bringing the total to 8.

Could name it Inu Buki; dog is the first animal I remember when I think of willpower and ability to last, maybe wolf is better.