'arrowless' is formed from the noun 'arrow' (modern English) plus the adjective-making suffix '-less' meaning 'without'.

'arrow' came into Middle English as 'arwe' from Old English 'earh' (or variants), eventually becoming modern English 'arrow'; the suffix '-less' derives from Old English '-lēas' meaning 'free from' or 'without', which developed into modern '-less'.

The components originally meant 'projectile' ('arrow') and 'without' ('-less'); combined they originally and still primarily mean 'without arrows' (literal), with later extended figurative uses like 'without direction'.