So I shall admit upfront to not having tried all of them, and I’m not even saying that the skills themselves are outright bad, you could clearly make builds with all of them if you were so inclined, it just feel weird to me that my response to unlocking most of them so far has been: Test, “meh,” go back to what I was using before.
I mean these are skills that are explicitly called out and limited when choosing your mastery, these should be something you can’t wait to get your hands on, not something you try once and ignore, especially with the way the devs talk about the importance of choosing your mastery as an event.
As to ways to improve them? my basic suggestion is to make them a sixth skill slot, then work on making them feel useful to varied builds. because if you just improve the skills and make them obligatory then things have actually gotten worse.
For some that could mean replacing the skill itself; taking the druid for example, mostly because it’s the class I played most recently, few people are going to want two different transformations (spriggan, bear) at once even if given one “free”, so switching the mastery skill to something else, and having the bear transformation just as another skill would avoid overlap.
For others it would mean tweaks to the skill to make it interesting to more builds, as a simple example, Meteor for sorcerers, is a fire only skill, so if you are playing a cold or lightning mage it’s unlikely to earn itself a slot, adding spec nodes to convert it would a simple starting point.