@rush99999 I believe this one is simple enough a task that a Society+Eloquence test would be all that is necessary. He is willing to offer a reward for successful assistance as is, but a Critical success will get you a notable mechanical reward rather than a narrative handwavium reward.
Least, near as I’ve double checked, that’d be the more correct way to handle this. D’arcy has limited access to funds and has a pretty cut and dry scenario; a more intense scenario or risk would be necessary to delve into the proper ‘Duel’ rules.
This is of course merely a suggestion for polite conversing or haggling. As always you could reframe it more physically or cunningly to try and use other Fields. Just the difficulty of certain things may be easier or harder etc. Trying to physically intimidate him for example would be quite hard, he’s a lieutenant in basically his base with his soldiers, etc. just establishing a vibe with these explanations.