Imagine a fast-paced multiplayer FPS game where every single player feels free to tune up all the weapons according to his personal preferences. Such a freedom could give him an option to create a weapon set of his choice, to build tactics and playstyle only around weapons which he is going to use and to master in further. Something similar was introduced with bringing up classes to FPS, but with classes player has only few degrees of freedom while my proposition gives him unlimited potential for self-realization within strongly balanced system.

- So, you have multiple modifiers for every weapon such as damage, projectile speed, reload rate and lots of others.
- Every modifier has its min and max values and can be fixed by player freely in this appropriate [min]...[max] range.
- By default all the modifiers are set to certain values and that results in default weapon set that has 1.0 effectivity value.
- Weapon set`s effectivity value is calculated from all the weapons effectivity values according to some formula. For example, it can be something like E = (E1 + E2 + ... + EN) / N or E = (E1 * E2 * ... * EN)^(1/N), where N - number of weapons. With default settings, all the weapons have some default effectivity values which should result in 1.0 if applied to this formula.
- Changing every modifier`s value to different from default one results in changing weapon`s effectivity value according to some complex formula, which could be found due to various assumptions and playtests.
- If modifier`s change brings advantage to player with using this weapon (for example increasing damage or decreasing reload rate), weapon`s effectivity value should increase by this complex formula, and vise versa.
- With making some weapon(s) stronger in such a way, you need to make another weapon(s) weaker to fit the overall weapon set`s effectivity value being less or equal than 1.0. That allows you to build weapon set of your preference while following the overall balance measure such as effectivity value top limit.

Pros and cons:
+ Unlimited potential for self-realization within fast-paced multiplayer FPS game.
+ Replacement of "weapon choice mastering skill" with "weapon of choice mastering skill".
+ Possibility of creating weapons`s so-called "Holy Grail" for every player and tweaking it out.
+ Less steep weapon`s learning curve for newcomers.
- The concept wouldnt work its best with current "quakish" set of weapons coz they arent that versatile as they could be. So, weapon set should be redone too.
- Various difficulties with finding proper formulas for weapons effectivity values.
- Hell of playtestings.
- Different modifier values from player to player that could results in netcode and serverside code requiring to be completely redone.

So, discuss :P

EDIT:
I assume formulas should be pretty complex to make all the things working quite well. For example formulas should implement progressive dependence curves, different mathematical powers for different modifiers depending on what weapon gets changed and dozens of other things to make sure players would not abuse only-one-weapon concept, especially with awful tendetions to build one-shot-one-kill hitscan weapons.