Hmn, most races have around 4-6 racials (Though there are oddballs like orcs having 3)
There's a...
Profession buff
Stat buff
Damage/Combat based
Utility
Flavor
Agreed on the mastery buff.
Some kind of 'active' self target heal over time spell works, instant might be too strong but channeled might be a nice tradeoff from Darkspear who have it as a passive. Another way to explore it might be to have Poison, Bleed, and Disease effects half reduced durations.
Honestly I think inscription works better for Zandalari's long history than Nightborne, but leatherworking works reasonably well too
They've got some stone/scale-like growth on their bodies, so perhaps a 1% decrease to physical damage? Maybe just from beasts or other trolls to keep it from getting OP?