The army of King Chnodomar is of particular interest to me though I'd be open to learning about all the others as well.
The only one I really no much about is the Anglo saxons.
I did a response about Roman armor during this period here.
Germanic armor would have been mostly the same. The one noticeable difference was that their chainmail was a bit lower in quality than Roman - it was still alternating riveted/punched, but it was usually larger links, so slightly weaker and easier to exploit.