[It's not as if Fionn never had to learn, certainly Bodhmall and Liath Luachra taught him many things in his youth. But being gifted with knowledge and wisdom by a magical fish did seem to render further study irrelevant, so he's definitely out of practice. And magic is a complicated subject that requires careful attention and patience. But he's not worried.]

Quite well, thank you.

[But of course he notices the bruises, and with a playful smile, points them out.]

But it seems I've had a dull night, compared to you.

[Because those bruises suggest to Fionn either a good fight or violent sex. Which is an exciting night either way. For better or for worse, he spares Diarmuid from having to properly respond by immediately jumping to the next topic.]

In any case, the classes seem entirely too tedious. I think things are better learned by practice, don't you?

[So in other words, trial and error.]