they are us it for gain a critical rate and some crit damage,
different from destroyer,magnus doesn't have rage burst ( rage burst only can be taken from mercenary,gladi,and destro class) ,so it better to use axe because they'll have axe morality skill (increase 10% crit damage and 80 crit rate).
but for destroyer,they are better to use sword because high level rage burst,lv 1 rage burst increases 15% crit damage (only works on swords),just compared with axe morality,rage burst is better,