Something that irritates me 19th century Germanic official documents: the variable typeface, such as the way an s appears on the page, depending on where it appears in the word. It looks like an s when it is at the end of a word, such as in "als," but looks like an l for anything else, such as in "Schweizerische." It looks really cool on the page, but makes it really hard on the modern reader to decipher.

And I won't even mention the handwriting.

(Yes, I am currently deciphering/translating an official document from 1864 Switzerland)