How strong did Neia Baraja become, and what caused it?

Question

So in Volume 13 of the light novel in Overlord, (spoilers)

it's clear that Neia gets stronger, however I'm not sure just how strong she becomes. For example, during the archery training, she manages to get perfect shots but indicates that she was not able to do so previously. Moreover, the first time she used the Heavy Recover spell, she was able to only use it once before running out of mana, but later she displays the ability to use it multiple times. If one were to compare her to the ranking system used by adventurers (copper, iron, bronze, etc., adamantite), where would she rank?

Also

I'm a bit confused on how the leveling system works in the New World. Ainz mentions that he is unable to increase his levels and XP by killing off over 100,000 soldiers in the battle with the Re-Estize Kingdom, so how can Neia get stronger?

Answer 1

About Neia:

During Volume 12, she only had levels as Squire and Archer. Squire is a special class that can have its levels converted into any other. After being resurrected and "converting" to the Ainz Cult, her levels as Squire turned into Paladin Lv. 2, Evangelist Lv. 2 and Founder Lv. 4, while her Archer class turned into Sacred Archer Lv. 3. Being overall Lv. 9, she'd be a low-middle-tier adventurer. Gazef Stronoff was judged by Ainz to be around Lv. 30, and he was considered to be stronger than the Blue Rose members, except maybe for Evil Eye. Her Archer class getting upgraded is probably the reason her aim got better (along with the Bow she got from Ainz), and her new Paladin class (and probably Evangelist and Founder) gave her some proficiency with healing magic, which is why she got better at using the Heavy Recover spell.

And about leveling

Ainz mentions that HE didn't gain any EXP from killing all those soldiers, but he doesn't know if it was because their levels were too low and he couldn't gain EXP from them or if there's another reason. We really don't know much about how leveling works in the New World, which is why Ainz was having that Death Knight train alongside Hamusuke, he wanted to know if Yggdrassil monsters/NPCs can learn Martial Arts or train in new classes; but so far, only Hamusuke was shown to be able to learn Martial Arts.