Is this a good winter tharja

Candleabra with Def refine probably better, but it's good.

I run mine as below as self sustaining tank. She gets buffed then takes the hits and Aethers herself back to health with the blade making up for her low attack. Atk Smoke also helps her tank multiple hits. She wants Armor March as her teammates need Hone/Fortify. I use her paired with Bold Fighter LA!Hector in GC/RR, he has Fortify Armour and Home Atk seal so they're a mobile team.