The Engineer's "support" career path contains a bit more esoteric batch of equipment: a handheld explosives defuser, enhanced NetBat ID computer and a plantable vehicle detector. This branch of the career tree is capped off by a powerful anti-armor rifle - but more on this later.
Your first unlock in this path, the AE Defuser, is handy in theory, but by the time you realize you need it, it's usually too late. Unlocks must be achieved in order, so you'll just have to swallow this one if you want the next few.
The next in the series - the NetBat Vehicle ID enhancement - allows you to track enemy vehicle movement and will keep them highlighted on your visor, even if they go behind an obstacle or cover for a short amount of time. You'll also share this information with your squadmates, which they'll likely appreciate. This enhancement gets permanently affixed to your kit when you select the Engineer class and there is no need to equip it.
Finally, the PDS-1 tracker unlock (the last before the Koenig H-AVR Heavy Anti-Vehicle Rifle), is a droppable UAV-like device that tracks enemy vehicles. This is quite useful if you are shuttling between two strategic points and need to keep an eye out for vehicles - but we'd suggest that if you are going to spend the time to drop something, it might as well be mines.