[ball]

You can't block weapon changing, but you can use SetPlayerArmedWeapon in timer or OnPlayerUpdate. Save player weapon and time in variables.

Код:

new theWeapon[MAX_PLAYERS], theTime[MAX_PLAYERS];

public OnPlayerWeaponShot(...)
{
	theWeapon[playerid] = weaponid;
	theTime[playerid] = gettime() + 3;
	return 1;
}

public OnPlayerUpdate(playerid)
{
	if(theTime[playerid] >= gettime())
	{
		SetPlayerArmedWeapon(playerid, theWeapon[playerid]);
	}
	return 1;
}

Something like this.