The reason I ask is that the feeling evoked by the term badass feels to me like a human universal, so ought to have synonyms in any era. Trying to confirm my hypothesis, I hunted through the Online Etymology Dictionary, where I hoped to find archaic substitutes, which unforunately did not provide me a direct history for badass. Instead, it directed me toward "bad + ass", which feels sort of strange to me since I'm not sure you can get the feeling of this word by breaking it down into constituents -- one needs real-life examples, really. The "bad" of badass seemed relevant towards the meaning, though, and here's what the Etymology Dictionary has to say:
[Bad's] [i]ronic use as a word of approval is said to be at least since 1890s orally, originally in Black Eng., emerging in print 1928 in a jazz context. It might have emerged from the ambivalence of expressions like bad nigger, used as a term of reproach by whites, but among blacks sometimes representing one who stood up to injustice, but in the U.S. West bad man also had a certain ambivalence:
These are the men who do most of the killing in frontier communities, yet it is a noteworthy fact that the men who are killed generally deserve their fate. [Farmer & Henley]
Right, so bad and hence badass is a modern term, with the former appearing no earlier than 1928, and the latter having a '70s era feel for me. My question is, what were people using to describe badasses like William the Conqueror, William Wallace, and Samuel Whittemorein their time?