She my be gifted in commander class that would be an explanation but considering her personnality that's difficult to believe and the level up is still too fast even for her low level and everytime she level up her Goblin are implique in the event, doing the majority of the job. Still Enri became stronger every time we see in a Volume so what is the reason ? It my be a talent but Enri was just a normal girl before meeting Ainz. Unlike Yggdrasil entity like Ainz who can gain at least 1 exp per soldier killed with the Dark Young regardless of level difference between them (Yggdrasil system), New Worlder like Enri gains the exp by effort, so just killing weaker than his summon would not give him much experience or no experience at all (this is the new World systeme and if it was not the case, the Sunlight scripture would have became the strongest scripture a long time ago with their focus an angel summoning and their mission related to demi-human extermination). Summons are considered an extension of the summoner, so they normally share the same rate of ganing experience as them, the summoner takes the exp from the summon (at least when it's a kill, a training may be different).
![overlord enri overlord enri](https://i.pinimg.com/736x/7f/60/8b/7f608b6a3db866cb81f27b7e421da2fe.jpg)
![overlord enri overlord enri](http://imgs.aixifan.com/o_1cn1ko1dv17qddtcd20nv5lnsq.png)
![overlord enri overlord enri](https://i.ytimg.com/vi/IOa2jI8Z0xk/maxresdefault.jpg)
Enri's leveling up is incredible, she gained 4 levels during volume 8 which take place on a period of only a few days.