There are open source implementations of both Morrowind and Arx Fatalis. That should be a no bullshit way to figure out their level scaling.

An alternative, if you don't want to get bogged down with formulae, is just to use a curve. It's designer friendly and quick to adjust, which is great for figuring out early development balance. Something like damage and attribute scaling is going to be dependent on your implementation of game systems - DPS for example is determined by attack speed, which'll likely be influenced by animations.