The latest round of adjustments to the elemental savant pre represents a golden opportunity to add a bit of pizazz to the otherwise underwhelming Sorcerer past life feats. My suggestion involves adjusting the passive past life feat to allow +1 stacking elemental weakness to your chosen element with a maximum of three. The active feat should be selectable for each of the elements, its effect should only proc the chosen element, and it should allow an additional +2 to the stacking of your chosen element. The total stacking should revert back to five.
You'll notice that the maximum available stacks in my suggestion is six, but the total would be capped at five. This is to allow some customizability in character builds allowing for +4 with no active feat, and +5 with the feat.