As a Reincarnated Aristocrat, I'll Use My Appraisal Skill to Rise in the World 4 (manga)  (English, Paperback, Inoue Natsumi)

It's brains over brawn in this new isekai adventure! One day when leaving work, a salaryman dies and is reborn in another world as the weak child of the noble Louvent family. Using his "appraisal" skill, which lets him see the stats of others, young Ars Louvent recruits the best people to his side in order to turn his country around.FATHER AND SONNow joined by his politically savvy fiancee, Ars continues striving to turn his weak domain's fortunes around with a little help from his talented vassals. However, everything changes overnight when Ars's father, Lord Raven, is struck by a sudden illness and the duke of Missian is assassinated. With Lord Raven out of action and war threatening at Missian's borders, is Ars prepared to take on his father's mantle?