As a Reincarnated Aristocrat, I'll Use My Appraisal Skill to Rise in the World 3 (light novel)

Ars Louvent, the young Baron of Lamberg, has a secret: he’s a reincarnated Japanese office worker! Though mediocre at best in the fields of swordplay and strategy, Ars has one thing that gives him a major leg up on his fellow nobles: a skill called Appraisal, which he uses to see past the biases and preconceptions of his peers and gather up a host of capable followers!

All is not well in his new home of Lamberg, however. Missian, the duchy Ars’s barony lies within, has been plunged into a war of succession, and circumstances have prompted Ars to join forces with Couran, the elder of two brothers vying for the position of duke. Like it or not, Ars is about to find him and his followers playing a pivotal role in battles the likes of which he’s never imagined!