OP here, account went preferred and haven't bought more gametime yet.
You still didn't get what I'm saying. Certain stats can only be exchanged for certain others. Take Enhancements, for example, as that is what is mainly affecting my main question.
An end-game enhancement has 3 stats. One is always Endurance. For the second you have a decision to make: Power, Critical, Defense or Absorption. And there's another decision for the third one: Accuracy, Alacrity, Shield and Surge.
End-game mods have 3 stats as well, Endurance, Mainstat (in the case of Sentinel, Strength) and Power/Critical/Defense/Absorption. Armorings only have 2 stats, Endurace and Mainstat.
There are also differences in the ratio of the stats. A DPS would always want mods, armorings and enhancements where the smallest number is Endurance. And as far as I know and recall, in enhancements, even if it is a low-endurance one, you still have to pick whether it has more Power/Critical/Defense/Absorption or Accuracy/Alacrity/Shield/Surge. (Feel free to correct me here, cannot be bothered to check it now.)
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So, there's no way I could assign my "leftover tertiary skill points" to Power. Because they cannot be exchanged with Power