First off, addweapon can only be done serverside, depending on if this is a level npc, or another weapon npc, you might just want to make the entire script serverside.
For detecting player chat, use if (player.chat == "chat")
One = sign denotes changing the variable.
And you shouldnt mix gs1 with gs2.
PHP Code:
say2 You already have a bank account!;
should be
PHP Code:
say2("You already have a bank account!");
And for detecting if a player already has the weapon, you can use
PHP Code:
if (player.weapons.index(findweapon("Weapon Name")) > 0)
Since if the player has the weapon, its index in the player.weapons array would be more than 0.
And you dont need to check the players chat again if the player doesnt have the weapon.
A simple "else" statement would do.
Edit: And i just read that the script is in the bank level, so you should just make the entire script serverside (Remove //#CLIENTSIDE), and it would work.