With balance in mind, here is a proposal for Psionic Mastery.
PSIONIC MASTERY
Level 11: You gain 9 special ‘mastery’ points, that are in a pool that is separate from the main pool of normal points.
Each discipline includes master level powers, that cost 9 points, 10 points, 11 points, or 13 points. Only mastery points can be used to manifest master powers. You cannot use normal points to master them.
If you use mastery points to manifest powers whose durations are simultaneous with each other, you can concentrate on all of them.
You can spend normal points to replenish your mastery points, but each time you do so, the mastery point total reduces by 1 point. For instance, you use your 9 mastery points to manifest a 9-point master power. When you replenish your mastery points you can only do so up to 8 mastery points total. Later you replenish your mastery points, but only up to 7 mastery points total. And so on. At each long rest, your mastery points return to your original total.
Level 13: Your mastery point total increases to 10. You can use them to manifest a 10 point power.
Level 15: Your mastery point total increases to 11. You can use them to manifest an 11 point power.
Level 17: Your mastery point total increases to 13. You can use them to manifest a 13 point power.
Something like that. This prevents spamming of 9th-level abilities. There are other creative ways to juggle the numbers − and maybe simpler − but these are the numbers in play for a full caster.
This is what a fullcaster progression looks like. Basically, they must be able to access the higher level spells for more impacting effects, at the appropriate levels. At the same time, they generally cast their highest level spell once.
Code:
[FONT=Courier New]Wizard Spell Level (Total points)
Level 6th 7th 8th 9th
11 1 9 points
13 1 1 19 points (9+10)
15 1 1 1 30 points (9+10+11)
17 1 1 1 1 43 points (9+10+11+13)
19 2 1 1 1 ...
[/FONT]
Basically, the full caster needs a 9th level spell slot at level 17. (It seems to me, the extra 6th level spell slot gained at level 19 is less significant in the context of the higher level spells, so less important for balance, and some other feature could easily substitute it. So we are focusing on what the fullcaster can do at level 17.)