If you don't want to buff his stats with an item, then give him a non-item, such as land or a title, even a promotion in his church. If it has to be a "found item", then it could be a deed that grants ownership of a piece of land or a noble title, or a non-magical relic which his church will promote him for, etc.
Land, titles, and the like should encourage him to roleplay and to develop more depth for his character without giving him any kind of bonus in combat. And to be fair, it could grant him an income, low-level followers, a reputation, etc. so that there is an actual reward there and not simply a clever way to bump his net worth without bumping his net "power".
If the title or promotion is specifically tied to his race or church, then it is not something that would be handed off to another character, so you can be sure it goes to him.
Similar ideas would be a boat, a building, a job, or claim to a mine.
Beyond that, an intelligent item (or adding intelligence to one of his existing items) is an easy "bonus" worth around that price point, and it doesn't have to boost him in combat. An intelligent item that has a mind of its own is a good way to hook the player into roleplaying occasional conflict with the item, etc. but still lets him enjoy the times when the item lets him do special tricks, which you can arrange to be non-combat tricks.
One final option for a half-orc would be an item that lets him change his race in a limited way. Specifically, a ring that lets him change into a full-blooded orc, a full-blooded human, or his natural half-orc status once per day, and it lasts 24 hours. It could have belonged to some previous half-orc that wanted to "fully understand his dual heritage", etc. If he's a powergamer, he'll probably figure out some uses for this in combat, but given that the effect can only be triggered once per day and lasts 24 hours, he won't be able to min-max it too much. The main point would be to broaden his character, let him experience life as a human, etc. maybe even motivate him to RP some racial angst etc, while still feeling like he got a really unique and powerful item*. (It's really not that powerful of an item. It basically removes the darkvision and racial adjustments or it pushes them even further into orc mode, at which point he would take the RP penalties that race entails.)
But he'd actually really appreciate a unique magical weapon.
