My spouse, who is German, offered Weichei (soft-boiled egg). (Note, if you don't speak German, it might look a little less weird if we pretend there's a hyphen: Weich-ei. Literally, soft egg.)
I also looked at the all-English thesaurus for synonyms for wimp. I've picked out some words that I am hopeful are authentic for that time period (but I can't swear to it):
milksop "effeminate spiritless man," late 14c.; literal sense "piece of bread soaked in milk" attested late 15c. Perhaps this is too gendered.
namby-pamby "weakly sentimental, insipidly pretty," 1745.
cream puff In figurative sense of "weakling, sissy," it is recorded from 1935.
sissy Meaning "effeminate man" is recorded from 1887; the adjective in this sense is from 1891.
What I like about cream puff is that it goes with French cuisine. What I don't like about it is that it doesn't seem to fit with the coarseness you're after.
-- Edit -- Added what I found at the site recommended by Mari-Lou. I also checked some dictionaries and it seems milksop is indeed too gendered, but sissy is okay.