Regarding the torpedo bats.
Unless I'm missing something... why would they be (or become) illegal?
It is nothing more than a shaping of the bat.
Bats have limits on length and diameter. Most bats tapper on the handle.
Physics says transfer of momentum and elastic collision. The heavier a bat the more distance you get... it also requires more strength... and conditioning to get through 162 Gs.
Historically the label is designed to represent the balance of the bat.. equal amount of wood on each side... this "sweet spot." The distance from handle end puts the sweet spot say 60% the distance of bat from handle.
So, if you taper the end and retain a larger diameter in the sweet spot, it will impact the momentum transfer. But, as I mentioned... that narrow top will cause more missed balls, but will also cause the ball to "go the other away." Like slicing a golf ball. Short RF could see a RHB get more HRs to RF.
Also, because the bat is only anchored on one side (handle) the physics of vibration and momentum are important.
At the end of the day... the length and weight of the bat (corked/hollow/cup) has been fluid over the decades... Pitchers will adjust. Just don't throw a meat pitch. LoL