@Choko おやすみ！

@DariusJahandarie There's also 大して

Martin writes only: "大した 'immense, important, serious, very', cf. adverb 大して―these being the only forms of what would appear to be a defective durative stative verb(al noun) *大する 'looms large'"

My dictionaries don't list an etymology for 大した

It seems to be surprisingly recent

The earliest citation in 日本国語大辞典 is 1885

And for 大して, the earliest citation is from 1869頃

Maybe someone just started saying one or the other and it caught on, and the other developed by analogy

Dunno. :-)