Not really a guide, but certainly a thought, for anyone who likes using staffs a lot. Hadn't seen anyone mention it, so I will.
We all know the White Wing Staff gains elemental charges with fewer bolts than the Trinity, and it seems that it might be able to hold charges longer as well (yet to be tested).
On the downside, the White Wing apparently can't be Special Upgraded, so it loses damage potential in comparison to the Trinity.
But, it seems that no-one has noticed that you can get the best of both worlds. Staff charges are actually a "status" type of thing on your character, not the staff. With this is mind...
1. Charge element with a Wing.
2. Swap to a Trinity.
3. Fight with said Trinity.
4. Swap back to Wing to retain charges for longer (untested).
5. Repeat 1-4 until you win (the game).
And there you have it.