High Lethality, low Attack

Hi everybody. One day, I was doing an EB custom battle as the romans, fighting the adeui. I was frequently frustrated when I would see three legionaries surround one levy spearman and stab at him for abount ten seconds before killing him. In that time, he was stabbed in the back frequently. I think it was around five times. It was annoying, because there is no way one could survive several gladius thrusts to the back, and keep on fighting. So, I thought about it for a while, and realized that the low lethality of the gladius was making the attacks ineffective. After thinking some more, I thought, "Maybe I can increase lethality and decrease attack. That should balance out the strength of a typical sword blow from the front, but from the back, where there is almonst no defence on an unarmored warrior, and where wether there is 6 or 12 attack, it will still defeat 1 defence very commonly, this change will increase the ratio of sword/spear/axe/etc blows to kills." In short, my goal is to increase the vulnerability of soldiers from the rear, while not changing the course of battle when the soldiers are facing each other.

Now, my question to everybody out there is, would doubling lethality on all weapons and halfing their attack strength accomplish this goal without many side effects. The only obvious problem I see is that this would make cavalry charges grossly overpowered, as it would mean that a Kontos for instance, would have .8 lethality, and still get 40+ attack due to the charge bonus. Thanks in advance for the help.