"Yes, we do indeed know about the war. Somewhat." (Buckthorn will try to get a sense if Yex had some sort of dog in this hunt or had taken a side) (Insight / Perception). If he doesn't sense Yex had any particular interest in the outcome, Buckthorn will regale the creature with tales of the heroic efforts, in particular highlighting the amazing skill of the archers and passing mention of the bravery and sacrifice of the many fallen melee troops under Forge's command.
If he seems amenable, Buckthorn will then ask the Yexil if he is familiar with these skies. "Perhaps, in exchange for the uniform cache, we might persuade you to fly as our escort to our destination - at least as far as you can. We aren't going far, though I will not lie, we are going to a ruin in the deadlands so you may not wish to accompany us all the way there, should you choose to come with us at all. But we would be grateful for your company. No telling what sort of evil creatures prowl these skies."