I don't really think the weapons cost that much. Especially since silvers are guaranteed to give you aetherpool outside of aetherpool sync, and there seems to be a higher drop rate of them per floor. Unlike in PotD where you could go an entire 10, 20, or even 30 floors with "Your aetherpool remains unchanged...".

For someone who isn't interested in doing the challenge floors, there's not much reason to hold on to 99/99 aetherpool, so spending 10/10 on grips and then building it back up takes very little time or effort. With PotD, it always seemed to take longer because of the increase's RNG.