Arthur Dayne Would Not Dual Wield

 Learned not long ago that dual wielding longswords is not a viable fighting style.

Ser Dayne did not get that memo.

If you think of the biophysics involved, it makes sense.  Basically, it puts you at a disadvantage relative to other things you could be doing with that off hand.

A longsword is a swinging weapon right? So you can't swing your off hand sword without getting out of position/balance for your next swing of your main hand. You trade a stronger swing for a weaker one, and you don't get an "extra" attack from it.

But you can use it defensively, you say?  Well for that, a shield would offer much better protection.

An offhand stabbing blade would also be a better option, because you could actually sneak an extra attack once in once in a while without putting your mainhand swing at a disadvantage.

Or, you could use your longsword with two hands on the blade, giving you more power and control.

Any of these gives you an advantage, as Ser Dayne would know. Plus, he has a pretty awesome sword made from a falling star, so why not use it?

I'm not mad, still loved the scene.  Just something that distracted me when I watched it.