Are you sure its 125? Because in my testing it seemed like it was more 135 as the power level max.
Sample testing example: normal levels 114/90 ----> using EPTW1 cause it to raise to the 135 unseeable cap, creating my lowest drain to be 85.
normal levels 104/80 -----> using EPTW1 cause it to raise to the 125 seeable cap, creates my lowest drain at 75.
So it seems like from testing that the 135 cap is still there.
i would suggest lowering what your weapon energy is set to and only using 2x EPtW 1, there is no benefit from energy elevated past ~135. i tried 2x EPtW3 and 2xEPtW 1 back to back, with my energy level at about 136 when using EPtW1. there was no difference when i tried EPtW3, it drained to the same levels.
if there was a real past 125 energy pool, i would be running 2 EPtW 3 all day long
One reason you may be seeing the large DPS increase from EPtW is the 5 second energy damage bonus it gives combined with fire at will. I think, but i'm not positive, that the entire duration of FaW gains the damage bonus which is considerable at higher ranks.