"Armored battle" would be the interpretation of
Brunhild or Brunhilda. I can see how the ending of Zerelda could go back to Germanic "hild", "Battle", as in
Griselda, but I can't see how you get Zer- out of Brun-. So unless someone can point me to another ancient Germanic word meaning something like "armor" that could lead to Zer- as a modern form, I would guess this is an incorrect guess. One would also have to link the use of Zerelda in the USA to the ancient Germanic roots somehow, and so far I haven't found any indication of the name being in use before around 1810, with almost all of the early examples being in Kentucky, which doesn't seem to indicate to me that an ancient Teutonic origin is likely.
I would assume that Maricel is a shortened form of
Maricela myself. Because of where the "i" is placed in Maricel, it seems more likely to me that it comes from
Maricela than from
Marcella or
Marcelina.