Add a function to set a player's weapon skill.
Like http://wiki.sa-mp.com/wiki/SetPlayerSkillLevel"> this function (//http) on SA-MP.
Maybe its included in ? (Docs are missing so i dont know if that's it...) (https://wiki.gtaconnected.com/Client/Functions/Ped/setPedStatsped.setPedStats%5B/url)
No, ped stats are also known as "https://wiki.gtaconnected.com/Resources/GTA3/PedStatspersonalities[/url]" (like cop, prostitute, etc)
EDIT: Figured I'd clarify this a bit.
In San Andreas, as you progress through the story your skill in weapons increases over time (as you use them).
You'll probably notice that when you start out, you hip-fire most weapons or have otherwise poor posture with them. Strafe is not possible while shooting, and accuracy is poor.
As the game progresses, CJ will eventually hold a weapon to fire more accurately, sometimes in a more "tactical" way. After a while things like strafing and firing, duel wield, and accurate fire over longer distances become possible. This can be altered in SA-MP using the function above.