Grugnak serves some time with the Company of Steel learning about combat and tactics beyond hitting things as hard as you can. As he is an aspiring knight, Lady Helen Kal also hires tutors to provide him with an appropriate education - he is going to be one of her husband’s knights after all.
He does indeed end up becoming a Knight, he doesn’t exactly exude the virtues of chivalry and gentlemanly behaviour but he tries his best and rarely causes more problems than an embarrassing incident. As a warrior on the battlefield however, he is terrifying to his enemies and inspiring to his allies - he becomes a champion of the Alvarium Kingdom and a leader in the military.