Ideas for Bane-related player rewards

I love to reward my players for RP choices, and I'll occasionally hand out extra feats, proficiencies, etc. for taking time in-game to learn something, do something, train for something, etc. 

One of my PCs (a Barbarian, no multiclass) decided to join the Church of Bane. I wrote a whole "taking the Oath of the Black Hand" scene for him, and rewarded him with the old UA Menacing feat after he agreed to receive the brand of Bane. It's been a couple levels since then, and he's made it a strong point to do things "in the name of Bane", invoking the "name of Bane" in combat, looking for religious factions of Bane wherever they go to see if he can do jobs for them...really making it a point to show his devotion. He has no interest in taking Paladin levels or anything, but I want to give him a little something from Bane in acknowledgement of his efforts. Anyone have any ideas? I'm at a loss for what to do outside of giving him items, which I'd rather not do. 

Maybe some kind of boon. Advantage on intimidation checks 1/long rest. Or bane will answer questions for him one time, he can cast commune once.

Or one of those local banite cults fund his reputation precedes him and are willing to help him with whatever he has going on.

Did a bit of reading on Bane and he has a raven who accompanies him who was called Koravis, so you could potentially give the barbarian access to the Find Familiar spell.

As a later option, Koravis apparently had access to "Smite Good", which could translate to it being able to cast one of the smite spells onto the barbarian once per long rest. Could be a powerful boost, though, so be wary of not overshadowing the others. Maybe start with the familiar and then have the option to smite emerge later, possibly at the cost of the familiar - having to re-summon it after each such use, and still limited to 1/long rest.