where do i find combatant fragment stone?

[wintry gull]

i did the quest at atanis and exchange the items for a weapon and armor, but i cant redo the quest to exchange the other 5

[jaunty slate]

You can only improve 1 Tuvala weapon and 1 Tuvala Armor with the combatant stuff. They are bit of a waste though cause need to melt Narchillan gear for those. Assuming you are talking about the Combatant Tuvala stuff.