Save is both a lexical verb ‘to know’ and also an auxiliary verb marking ability or habitual.
The first attested use of save with the meaning 'know' is 1872; the first attested use of it as a verbal auxiliary (ability) is in 1859 [published in 1873].
Source: Meyerhoff nd
Source: Moresby 1876: 96
Source: McFarlane 1873: 106