Kind of weird, one of those things you dont plan but on the course of playing you just realize...I always felt that the right hand dagger animation was kind of lumbering swing, more fit for a short sword (miss those...a lot) than a dagger but what could you do about it right?
Well while I was trasnmulting some ore I got attacked by a Forsworn and in my confusion over the seemingly empty camp I just put a dagger on my left and attacked back, only to notice that if you have a dagger on your left hand your char does a little side swipe and then a proper thusting stab...not only is this much faster for attacking, but visualy more pleasing.
So one more thing that I never thought possible, that the game developed for my char over the course of simply playing...no planning or ideas, just playing, having fun and letting it flow

I thought the uesp said the left hand swings slower.

I am disappointed that you can't select a primary hand to switch what side your bow and two-handed weapons are held on and the faster of your arms when it comes to one-handed combat. It'd also be nice if you could hold a shield on your right hand instead of it being forced to your left.

yeah i dual weild alot and the left is almost always slower
I wish we could have these features