If you worry about the DPS value displayed on the character page, don't let that bother you. It doesn't accurately reflect how useful skills like Panetti's is. Surely it is not going to feel smashingly powerful against single bosses, especially melee ones, yet it is a sustainable skill if developed right. When fully upgraded, and later with the help of skill bossting items, it grows into a huge crowd control skill. And crowd control should be a squishy character's primary attribute. Or else even petty harpies are going to come too close and dish out large chunks of hp.
Panetti's deals elemental damage and aether damage. When picking up equipment, try to find stuff with bonuses on these. Remember, your weapon isn't going to be used for melee. So, just consider how much boost you get from it for these two damage types. I don't know if you are using a shield, but consider dropping it if you do. Instead use tomes, offhands and implements.
Also remember that you can always respec Panetti's and redistribute skills as you wish. However, note that I have a lvl 85 battlemage character with whom I made it all the way to Loghorrean and kicked his ass on ultimate difficulty without dieing a single time. And from the beginning to the end, I used Panetti's. It is really useful and sustainable.
