Complex sentence: The chivalrous countries in western Europe considered the tactic to be underhanded, whilst Eastern armies considered it a key skill: the Byzantine general Belisarius was particularly noted for using deception against overwhelming odds.
Split into simpler sentences: The chivalrous countries in western Europe considered the tactic to be underhand. Whilst Eastern armies considered it a key skill; the Byzantine general Belisarius was particularly noted for using deception against overwhelming odds.