na-adjective
Archaic adjectival noun meaning gentle or lenient. In modern Japanese, this form is obsolete; the polite expression お手柔らかに (おてやわらかに) is used instead, often as a set phrase meaning 'please be gentle' or 'go easy on me'.
See also: お手柔らかに
In old documents, 手柔らかに is sometimes written, but in modern times お手柔らかに is common.