Maybe a dumb question.

So I’ve been building lists and as we all know our sword brothers have gotten quite the upgrade. Looking at it in the app it says that the sword brothers are lead by a Castellan. So my question is if out sgt equivalent is being named as a Castellan does that mean we basically have 2 characters leading it? Do we use their abilities in conjunction with whatever other leader you throw on em? Can the built in Castellan take enchantment war gear? Or did they just have to call it something besides a sword brother sgt?