Behold! A perfectly ordinary wetland. Grass, trees, boggy knee-deep water, pond scum, mud, fog, everything a person could possibly want in their swamp.
So, he could refrain from jumping on this opportunity, or he could jump on it.
... Well, if Vun wants his advice, legion reforms, underofficer training, pike infantry, the longbow and a number of other developments will all function quite well under the circumstances. There's other things that he might be able to do - in armor, for instance - but he'd want to talk to metal-mages about that.
So the fundamental idea is that by using a bow made out of the right wood - which they might have trouble tracking down, but wood-elementals might just be able to make - you can get something that can take the full strength of an archer regardless of how strong he is, and use that to drive an arrow. Rates of fire are very impressive; the main weaknesses are armor penetration and that longbows-and-quivers are fairly bulky, limiting the weight of secondary weapons an archer can carry in a fight.
He doesn't know their name for it, so he'll want to look at a lot of different woods so he can see if any of them match.
(You can also make a very expensive but even stronger bow out of wood, horn, and sinew, but you can't have wood-mages mass produce it.)
He thinks so!
(Does Vun intend to bring up the subject of salary and/or rewards and/or promotions for the person telling him all this?)
Well, Durante will bring it up only insofar as he needs to make excuses, due to his duties with the Guard and with his students tragically preventing him from devoting as much time as he would like to this project. And perhaps also very indirectly if someone asks how his homeland does projects, since it does indeed do them by hiring experts and paying them lots of money.
(Are there other people at the table? If so, what do they have to say on all these subjects?)
He can leave his guard contract after any festival if he has somewhere else lined up; he's not intending to stay in one place forever, even one as nice as this; he likes travel and adventure and danger and exploring new lands.
Taxes, yes, and tribute from neighbors.
A wood bow is easy and inexpensive to make, a composite bow is very hard and expensive, and archers need training but most of that is strength-building.
Either you win a war with an enemy state and demand tribute, or you offer to defend a weaker state from its neighbors in exchange for it paying you tribute to help pay for the armies defending it.
And they didn't immediately begin fighting wars with each other over pre-imperial claims to hegemony and/or attempts to restore old borders?
... But they're currently at peace?
... Durante is happy to hear allll about it.
He will listen! When they have said what they have to say he will change the topic, either to something else they want to talk about or to one of the many stories he has to tell on his own.
Durante can still laugh. (He's very good at laughing at other people's jokes.) Do they know the one about the man who came home after a long journey...
Oh. Well, he's in bed with his wife, who he hasn't seen in ages, and a naked man with a knife leaps out of the closet (he'll use whatever the best translation of "wardrobe" is, actually) and says, "I am the fugitive criminal Gabriel!" and runs through the door. A few seconds later another naked man jumps out and says "I'm guard officer Arthur, did you see where the fugitive criminal Gabriel went?" and the very confused man points.
"Thank you, citizen! Guard squad, after me!"