You'd prefer one of those "Could Old Nan beat Lady Olenna if they both had Valyrian swords?" topics? Maybe a Frey who's not a total slimeball is just refreshing.
I think this is a topic worth of a lengthy thread:
Which of our favorite grans from ASOIAF would win in a duel if both were wielding Valyrian greatswords?
My first instinct would go to Olenna, since i think she can be a lot meaner, when it counts.
BUT one can not forget old Nan. Maybe Dunk showed her a few tricks after she showed him a few. We will find out in the she-wolves.
So far my money would be on Olenna!