In addition to lethality I also want to add in that quick knife is lame.
Taking out a knife is no more rapid than taking out a pistol. It's a decision to switch weapons and switching has a cost in time for every weapon - the knife should be no different. It also remove sthe possibility for a bayonette to be a useful addon. The value of the bayonette is that its already out and ready-for-use. It is a true quick-knife, and if you have a weapon that allows it or its an upgrade then great, that's a meaningful advantage. Just say no to quick knife.
Also, having an insta kill knife would put a lot of power into the hands of infiltrators, and the counter to that will likley be more anti-infiltration options.
The melee booster implant is another thing to bring back. If someone wants to be effective with the knife, then get the appropriate equipment and implants and boost it.
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