I was musing upon the Northern English/Lowland Scots word sair, a dialectal form of Mod Eng sore, as in the old-fashioned "sore afraid." And suddenly it occurred to me that sair as used in the Border region behaves uncommonly like German sehr, "very." So I looked the etymology up, and yep, sair and sore and sehr are all cognates.
The primary meaning was "injury, ache" but acquired an adverbial use which came to mean "very." In German, the adverbial use became primary, while in English the adverbial use faded away except in dialectal forms and the idiom of the King James Bible.