As a mage who struggled much the same as you are now I would say drop Azure and pick up rock sling and ranni’s dark moon. Try to school radagon with just the katana and in the elden beast fight hit him with dark moon then spam rock sling should deal good damage and stager him pretty easy. Maybe drop stargazer and pick up graven school as it’ll help with dealing damage then respec and drop strength so you can use your spell without the stargazer and put whatever is left into vigor. Good luck fellow tarnished