My mom and I had a little talk about the Fullmetal Alchemist Play Arts Kai as well as how Roy and Ed both lacked certain accessories.
Digging into my old stash of Highschool bootleg toys (Yeah, sadly. Those were my days as a noob Otaku), I found the accessories which in the end, satisfied us both.
Roy Mustang: Flame Trail
Edward Elric: Thunder Sparks
Yeah, I know it looks kinda like vomit. Bear with me for a while. I'll paint it over with Tamiya Clear Blue when I get the chance.
...and thanks a lot to my mom for the cool idea.