I feel like the Heirloom Ring is a little bit underpowered, it's a one time use that can't be brought back so I think it should either recover all Omen or gain 4 Omen (not recover). Because there is now so many other way to reover Omen.
Yeah. The nature of designing this game over a long period of time has made it so that some Specialties lag behind others, and also made it difficult to patch older books due to the layout software.
You could lean into this by making it so that when you gain a Specialty, you roll randomly on that Class's Specialties chart, but it's also perfectly fine to issue spot buffs if a Specialty doesn't feel interesting. I think the ring giving a small damage bonus on spells could be good, and also having it teach you a spell when it breaks.