They just look like oversized generic Gremlin heads, but they've been in the files forever and they come in the standard color schemes. They also come in Trojan head varieties, and I have a nice image of Crazyoddbaa wearing one of the Trojan heads, proving that they do exist as an in-game item, but are GM-exclusive ATM.

Most Gremlins don't wear shields anyway, and people tend to hate the ones that do (e.g. Mortafires, grr...).

Well you have to get a darkfang shield Mr.Razwog.. I'd go with the seerus mask, and perhaps shadowslicker? Not sure.

If you want a darkfang shield, it shouldn't be too hard to get; it might take you a few months of grinding, but here is how-

Step 1: If you're F2P, farm FSC a few dozen times to have excess CE. Lots, and lots, of excess CE; you're going to be wasteful. If you're P2P, you can just purchase an Epass and run T1 instead; you'll need minerals. Earn the gremlin ones; I forget which they are but go with people to get them.
Step 2: Allign 2 gremlin stratums in S4 and S5; early T3 and late T2.
Step 3: Make certain that there are 2+ arenas in both S4 and S5. If not, try again.
Step 4: Skip to the terminal of T2 on said gremlin gate, and then solo a few hundred times through all of the arenas.

Gremlin minerals are Red and Blue, anti-purple. Aka need to have red and blue as the highest two mineral counts, and purple as NOT the third highest.