After a few iteration, I think I'm starting to get the gist of Lora creation, even if it's far from perfect.

This one was trained on about 100 images, extracted for gelbooru, with a bit of manual images & tags pruning.

Prompting should include "megumin", and can be equiped using :

witch hat, cape, staff

The staff itself might get a bit weird, but inpainting it using only "staff" as a prompt, without mentionning megumin, should give better result.