I recommend having the fight be in a canyon between glaciers, with the bottom open to the dark foreboding arctic sea. Its one thing to dual wield, another to do it while climbing, and if they use spider climb or the like, the dragon uses spells or ice shape to slide the ice wall down into the sea. The dragon can ice walk to make up for poor flying conditions, and there should be a blizzard to obscure visibility.
Use the burrow speed to attack from inside the glacier, and swim speed to take to the sea. Whatever they cannot follow becomes safe haven
Let the dragon raid consumables from its hoard under the sea or in a hollow inside the glacier.
Choose spells that let the dragon set up permanent advantages in its lair. a stunn or loss of actions could mean they fall off the canyon wall. Loathsome veil is good. Symbol of stunning is better.
Some kind of sea creatures could inhabit the lower canyon, or some other creature could be bullied into being an ally. It needs something.
Worst case scenario: the dragon has a mate. Doesnt even have to be the same age catagory, just one or two lower to round out action economy.
High wind can make archery difficult or impossible, but will also make flying hard. The dragon has infinate Control Weather to set this up.
disarm weapons and drop them in the sea.
Suggestion Spell: go for a refreshing swim.
Plenty of defensive spells like mirror image and displacement.
The key is that the long drop with sheer walls gives the dragon a mobility advantage again without being a flying kite again.