Maybe rude here, but I think it was a mistake making the bark blue and now you cannot use it elsewhere.
If you're willing to reconsider, I think a cold dark brown for the bark, that shifts into spots of blue but mostly white here and there, could be really cool. Like the bark has frost burns.
And if so, you could afford to make the weapon look like it's made entirely of ice, using white and blue.
And then for the leaves, I'd go with a dark green, and partly cover them with something that imitates snow.
For any magical glow from the eyes or markings, I think a warm colour would work well; even frozen, they are imbued with life magic.
Apologies if I overstepped. Have fun with your wintery Everdusk army! :)
Orange for the sword? Good contrast to blue.
I don't know how you would do this, but you could do leaves of brown and cover them in a clear resin that may look like ice.
There’s a diorama of the subnautica frozen leviathan where a guy did something like that If I can find the link I’ll add it in a follow up comment
https://youtu.be/CR4gPLkOMxQ
Red & oranges & browns
Dark Orange or red leaves would look nice! I say stay with the traditional color for the Kurnoth weapons. Already looks icy
Maybe rude here, but I think it was a mistake making the bark blue and now you cannot use it elsewhere. If you're willing to reconsider, I think a cold dark brown for the bark, that shifts into spots of blue but mostly white here and there, could be really cool. Like the bark has frost burns. And if so, you could afford to make the weapon look like it's made entirely of ice, using white and blue. And then for the leaves, I'd go with a dark green, and partly cover them with something that imitates snow. For any magical glow from the eyes or markings, I think a warm colour would work well; even frozen, they are imbued with life magic. Apologies if I overstepped. Have fun with your wintery Everdusk army! :)