An Etymological Dictionary of the German Language/Annotated/schwer
schwer, adjective, ‘grievous, heavy, difficult,’ from Middle High German swœre, adjective, Old High German swâri, swâr, adjective, ‘heavy,’ with the adverb form Old High German swâro, Middle High German swâre; Old Saxon swâr, Dutch zwaar, Anglo-Saxon swœ̂r, swâr, Old Icelandic svárr, ‘heavy.’ Akin also to Gothic swêrs, ‘honoured, respected, weighty, as it were, for heart and sense’?. See wichtig, Gewicht. Compare Lithuanian sweriù (svèrti), ‘to lift, weigh,’ swarùs, ‘heavy,’ svóras, sváras, ‘weight.’