I never thought about derivation of word "quaint"
quaint
adj.
5ME cointe < OFr < L cognitus, known: see COGNITION6
1 orig., clever or skilled
2 [Now Rare] wrought with skill; ingenious
3 unusual or old-fashioned in a pleasing way
4 singular; unusual; curious
5 fanciful; whimsical
quaint$ly
adv.
quaint4ness
n.