Originally Posted by
Kazela
Eh, wouldn't worry about that too much, because unless you're spam running Aetherochemical and/or Antitower, eso tomes become the limiting factor in progressing on the 240 step.
Speaking of that step:
Once you're at 120/240, you'll get a cut scene where the weapon actually starts to welcome the power additions you've been doing. This in turn unlocks the capability of getting bonus dust from each turn in. I've had 2 turn ins where I got a +2 bonus (so 5 dust instead of the normal 3).