Autobot/Decepticon Elite Guard

I have a little project going that involves the use of the Elite Guard insignia (specifically the Decepticon variant), and it has me thinking on the origins/use of it. Note that I'm not that versed in Transformers lore...something I'm trying to remedy. I've learned that it's essentially their military insignia for those Cybertronians who graduated the Autobot Academy. However, I've read somewhere that it's 'fallen out of use'. I'm assuming from the actions on part of the Decepticons. Which doesn't exactly make it clear how the Decepticon variant exists, unless I'm to assume they simply adopted it with alteration.
Anyone mind giving a quick rundown on it, please?
Anyone mind giving a quick rundown on it, please?