I find the current implementation of runes disappointing
While I can see how changing to the charge system can be seen as an overall improvement, both allowing players more control of how runes are used as well as adding resource management and letting the player decide when and how to use rune's powerful effect. However, in practice, what we currently have feels quite lackluster compared to how it used to feel when we had proc on smite.
The first and biggest problem to me is that in all simpler runes that add additional damage bonus, they are now limited to a single heavy attack. So instead of, for example, slaying a group of enemies, swinging around a cool fiery sword, and maybe even throwing it at someone and seeing a nice explosion of fire as it pierces their head, I am now limited to a single animation that essentially is just a lot of extra damage once, losing most of the cool factor to me and making it feel kind of like limited charge targeted ability that is saved up for stronger enemies. Or same , just boring single, a lot of damage shot, instead of unleashing a rain of arcane arrows obliterating my foes, which admittedly might have been a tad too strong, but at least it was fun.
The second problem is that it feels clunky to use, having to hold another button at the same time doesn't feel right. For that one I see an easy fix: just have a quick channel (like 0.3s) when holding spectral sight and heavy attack, and the next heavy attack after is empowered, if it is aborted midswing charge is just returned.
For the first one, it might not be that easy, but I would rather have rune activation still empower all attacks for a period, maybe for a shorter period or with a smaller multiplier to compensate. Rune activation that way can still be tied to expending a charge with quick channel on holding spectral sight + heavy attack.