So I was thinking about how utterly useless pets are compared to thralls since thralls can be outfitted and armed to be far superior.
Something I think could work, and still remain within the bounds of game lore etc, are one-time use “training books”. Make them drops, or craftable, or a bit of both. Unlike thrall armor and weapons, it would need to be permanent but any ability to upgrade pets would be appreciated.
I know you still have to make thralls better in some respects due to the “capture vs taming pen” bit, but as it stands pets are all but useless and it seems a shame to see that work get wasted.