Its a very difficult one this because well kitted tao can do very very nice damage and kill faster than some other classes in the right places.
so boosting the lower ones with craftable amus would also boost the higher ones into a potential OP state. I don't mean War/Wiz OP levels but more of a support class being able to produce real damage rather than control would break the meaning of that class.
I suggested once before for a new Pet to replace the dog, no master commands. at level 0 it is equivalent to a level 7 dog.. at level 7 it would be quite a fearful companion.
Id suggest levels 45 - 47 and 50.
How about instead of being a specific increase, it was a % based one, but inverted. Basically (100% minus your max SC) / 5. So at 20sc you could get 80/5, therefore 16sc. The higher your SC the less powerful the buff becomes. A short duration to make sure it's not abused by people removing gear (or recalc it on the fly?). Could also be tied to group size, divide by 5 multiplied by group size, so 5 for solo, 10 for duoing, 15 for trio, etc.
A new pet would be cool, though it should probably only be usable while ungrouped and be instagibed by bosses. Designed as a leveling pet, so lower level imo, maybe 30 for lvl0, 40 for lvl1, 50 for lvl2, 55 for lvl3 and make it's stats scale accordingly?
Being a support tao should be a personal choice, not a fundamental aspect of the class. Every other class has the option of soloing OR grouping, taos deserve the same choice.
Alternatively, make Holy worth getting by making it luck vs undead? Think of it like healing undead in many old RPG systems. Taos should be "the" killers of undead, they are basically polar opposites. Why Wizzies were given TU I will never understand, but that's beside the point! Holy being DC vs undead is fairly worthless, and modifying it would make it a far more interesting stat choice. Going full holy might mean more levelling speed, but your PvP damage, and damage in other levelling areas would vastly suffer.