I would say it's a baby one, and adjust as follows:
It's a baby one. It has 4x your Ranger level in HP, even from levels 1-5. It has 2 lower strength than normal (so 14 Str, +4 on hit, 1d4+2 base damage, same as a Panther), and it does not cover their mouth, so they can still breathe. Depending, Damon Tor's suggestion might still be needed.

Personally I'd probably start it tiny, having an even lower strength, like kitten-esque, from 1-2, and no Darkness Aura at those levels. At 3 it would be as described. I'd likely then phase out my nerfs, and turn it into a normal one, as you went higher in level (since BM hunters need some love imho anyway) and eventually fade out Damon Tor's as well as it grew more experienced in combat. To me that would still be fun, interesting, and playable, and not OP to a problematic extent. That being said, depending on the DM's enemy selection, blindness could matter a lot more or less than expected, and that would in turn affect the relative power of it, so whatever is determined, I would walk into it with the expectation of tweaks being done if needed.