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.

Could be able to cast Bane 1/day, lol.

Since Bane is the god of tyranny and whatever, I imagine it would be something along the lines of subjugating others. Command, fear aura, those kinds of things. You could borrow some stuff from the Xanathar paladin subclass Oath of Conquest, which is basically a Bane paladin. Just don't throw in too much, or you might turn the roleplaying into a mindless hunt for more rewards, which would drain the fun.

I'd suggest focusing on RP rewards rather than mechanical rewards since the player seems into the RP aspect and is involving Bane in the RP aspect. For RP rewards I mean stuff like:

• A new initiate of Bane seeks of the Barbarian hoping to train with / learn from him.
• A local church of Bane seeks out the Barbarian for help with some problem.
• Being inducted into the Church of Bane and being given a holy mission such as being told about lost relics, sent to hunt down enemies of the Church of Bane, or being sent to conquer a village in the name of Bane.
• Having some holy clerics that follow the a god that is an enemy of Bane find out about him and get into a theological argument with him in a tavern / public square.
  • Bonus: have these holy clerics be involved in a quest the party is pursuing
• Have Bane himself send omens or messages to the Barbarian praising his good work.
• Put in some rival NPCs that threaten to attack the party but change their demeanor upon seeing the Barbarian's mark.
• Create a little side plot involving the church of Bane - perhaps one of their churches gets destroyed and the party have to figure out who did it and why.
• Start having regular peasants or other NPCs react to recognizing the Barbarian as a follower of Bane.

Thanks for the ideas :) Trying to avoid spells since he can't concentrate while raging, which would really limit things like casting bane or some of the smite spells. 

Quote from Xalthu >>

Or bane will answer questions for him one time, he can cast commune once. 

Really like giving him a one time commune, will probably go with this. Thanks!!