Python, your question is about accents.
Neither classical nor koine greek had (written) accents prior to around the 6th century CE, when they were invented (that's approximate; some diacriticals [the technical name for the set of marks including acccents and breathing marks] appeared before others, and they developed and standardized over 3 or 4 centuries). Ahadams is right that most of the manuscripts of ancient Greek documents, including early Christian documents, have them; but most of those are late copies of copies of copies (etc.); none of the earliest manuscripts do.
The style of script in your proposed tattoo is the all-capital "Uncial" manuscript style of all ancient formal and literary documents. There would have been no accents; indeed, there would not have been any separation between the words. The standard style was In Scripto Continua, just a long string of capital letters. The reader was left to sort out where words, sentences, paragraphs etc. all began and ended. No punctuation or anything. Reading was a real skill back in the day.
The quotation comes from Herodotus, doesn't it? Or is it Thucydides? Either way, it would have been, both originally and for several hundred years, the Uncial type of text I've described.
CG