Okay, I've had something in mind for a while, so here it is:
Name: Sentry Missile (Replaces Dive Missile)
Colors: Dark Blue and White
Function: It fires a slow moving rocket that goes in a straight line once fired. During that time, if it detects a player, it launches rather quickly towards that player for 30 damage. It has 5 uses, and 100 ammo. That means that it uses 20 per Sentry Missile, and it's kind of difficult to get ammo for it unless you have W Tanks. For this reason, it's recommended to place this weapon in a map designed around it to have control over how many W Tanks there should be and where. Additionally, it has a very slow rate of fire.
Once you fire a Sentry Missile, you must wait 5 seconds to fire another or to switch to a weapon. This is best used with prediction. After a while of traveling though, it will dissapear. This can be adjusted accordingly.