adverb
Indicates extent or degree, often used in literary or formal contexts. Similar to それほど, but more emphatic or old-fashioned.
さばかりのことで怒るとは思わなかった。
I didn't think you would get angry over something of that degree.
adverb
Emphasizes a large quantity or intensity, often with a nuance of surprise or admiration. Can be replaced by それほど or あれほど in modern speech.
さばかり努力したのに、結果が出なかった。
I tried so hard, but got no results.
Derived from the classical Japanese adverb さ (so, that) combined with ばかり (approximately, about). The exact historical development is uncertain, but it has been used since the Heian period.