The detached, flowing sleeves read very Dawnish in their cut and not very Wintermark. As Batmage suggests, I think making it more of a solid tunic would fit better, and as well as holes at the shoulders you might cut a smaller V shape into the cuffs to mimic the slits in a way that doesn’t draw it towards another nation brief.
I’m not 100% on the slit in the skirt - I don’t think it strictly feels wrong for Wintermark but I don’t know the exact intricacies of the WM kit brief. Maybe consider a rougher but similar shape achieved by having the skirt almost-overlapping rather than being actually slit (not sure if that makes sense…)
I adore the feathered vest piece. It screams Kallevesi in a really unique and eye-catching way. The crossing belts also provide a great place to hang the typical Kallevesi bits and pieces.
And yeah, a head-dress is iconic of WM priests, but for the time being maybe just emphasize the feathers in your hair (I’d recommend giving them some visible means of attachment to draw attention to them and make obvious they are Priesty Accessories and not naga feathers or anything). You can build up to a more solid headpiece later if you like. Evolving kit is fun.