'welt' (shoe-strip sense) likely originates from Middle Dutch or Middle Low German 'welt' meaning 'strip' or 'ridge'; the skin-mark sense is related to the word 'weal' from Old English.

'welt' (strip) passed into Middle English from Middle Dutch/Middle Low German 'welt' and became the modern English 'welt'; the skin-mark sense is historically tied to Old English 'wela'/'weal', which gave Middle English 'wele'/'weal' and later alternated with 'welt'.

Originally used for a ridge or strip (especially in shoemaking), and separately for a raised skin ridge (weal); both senses have persisted into modern English as related but distinct meanings.