Aetherhearts and Aethersparks will not be continuing in the Awakening update, as we will no longer have the reforge system.
Power boosting armour will ensure it comes over to the new system at level 10 instead of level 1. Power boosting weapons will help contribute towards reaching weapon totals to be rewarded weapon tokens for the update. Read more here:
https://playdauntless.com/news/awakening-date-reveal/
Given that, I'd definitely recommend you spend them now, either power surging weapons till you have enough to maximize your gain of weapon tokens, or to set up more of your armour to come through at level 10 in the update!