While I really like the indirect levelling idea, I'm worried it's getting a bit too mechanically complex a Divinus Lite. But if we're going with it

1-2 - 2 Might
2-3 - 4 Might
3-4 - 6 Might
4-5 - 8 Might
5-6 - 10 Might
6-7 - 12 Might
7-8 - 14 Might
8-9 - 16 Might
9-10 - 18 Might
10-11 - 20 Might

Each level effectively requires 2 more than the previous one. It very quickly becomes more taxing than the present system, but unlike the present system it's Might spent on other things rather than levelling directly.
I'm no mathematician, but doesn't this, once you get to about level 10, make levelling extremely difficult? I don't remember the last time I spent 20 Might in a single turn, or even 2  turns or 3