Are you talking about the hex driver for Trijicon night sights? That is just a 3/16" hex screw driver.
I have one, but I am in Vancouver. I think you could find this pretty much wherever tools are sold, or, order one from one of those GLOCK parts places. The screw-type front sight will always come loose eventually with blue loctite, so you have to keep re-tightening (and loctiting probably) about once a year if you shoot a fair bit.
I believe Meprolight and some of the others use the same kind of hex screw on the front sights. The plastic factory ones just sort of pop in, and have a little plastic "pin" which in theory does something to hold it in. The GLOCK factory night sights need a special tool to stake them on, and those are a pain. Unless they have changed it in recent years and gotten with the times.
I would personally prefer that they use a dovetail like the rear sight, but, I guess they don't want to.