RubberPeen
Book of knowledge could have a lot of potential; especially if he creates a small isolated server with all those memories. He could use them then redownload them from his own server. It's also the only real unique power. He can easily get laws power through the system; he also can't really use laws power in his fighting style- Nor as a doctor. Downside of living in a sitcom instead of supernatural world. Plus telekinesis has more potential. Telekinesis if he can get more precision & control could allow for him to simply rearrange matter at will. Making laws abilities irrelevant. The ability enhancement power- Is sorta the inverse of the knowledge power. It's an ability focused more on instant gains; rather then growth. If he was actually in Hunter X Hunter... He'd need to focus more on immediate gains. However he's got far more leeway with the system given powers. He can eventually but the boosted gear; or a twice critical for example.
How about the ability of this guy from this fanfic * my researching journey (hxh)* that will make him overpowered overtime as he travel from world to world.As I am seeing him going through the researcher and the doctor route. Besides he should be smart, right? he shouldn't limit himself with those vows.