According to lore, would magicka Nightblades who are in essence shadow mages, be among the skilled and powerful sorcerers of Telvanni or the mages of Alinor? Would you ever find a shadow mage studying their powers in a scientific way as other sorcerers do? I feel like the art itself is not studied but used out of instinct by the various assassin guilds of Tamriel, not really accepted as mainstream sorcery by the 'real' mages.