Sorry to wander slightly from the subject , but I have encountered some heated debate and controversy recently , regarding the spelling of a warship's Latin "motto" . Beneath the ship's "crest" ( wrong word heraldically speaking ,but nevertheless in common usage ) of the carrier HMS Eagle ,are the words " Arduus Ad Solem " . However, a manufacturer of gold wire blazer badges has misrepresented it as "Arduis Ad Solem" . Is this another example of an ablative plural ??