[BigGroter]

pawn Код:

if(sscanf(params,"uid",Weapid,amt)) return SCM(playerid,0xff0000FF,"Usage /givewep [playerid] [weaponid] [ammo]");

You need to add Target before Weapid and amt.
Like such.

pawn Код:

if(sscanf(params,"uid",Target,Weapid,amt)) return SCM(playerid,0xff0000FF,"Usage /givewep [playerid] [weaponid] [ammo]");