Crusader Kings 3 EP7: Lumpy

One thing of note is that barony tier vassal serve at will you can outright revoke their title and give them to more talented people.

The primary way of attracting talented people is marrying them to your current court members. Just make sure the your current court member’s dynasty is dominant in the marriage. As in marry your female courtiers matrilineally and vice versa.

Lastly unlanded courtiers are really unlikely to have kids, so if you are are aiming to start a eugenics program, give your newly married talented subjects barony titles.