Destroyer emblem and Fishron wings are great, keep those.
Whether Arcane Flower is right for you depends on how you play, if it feels good to use then do not change it, if you want some other mana accessories try Celestial Cuffs or Magnet Flower but they both need the Celestial Magnet.
Celestial emblem is a good choice to go with your Arcane Flower, since the pickup range increase does not stack.
Terraspark boots are amazing for moving around in lava and other tough areas, but unless you plan on doing the fight over a pool of lava it is not as good as Amphibian Boots, if you feel like fishing fishing for the Frog Leg it is a better pick for combat situations because it makes you fly up faster.
Avenger Emblem could be replaced with a Sorcerer emblem for 3% more damage, but if you are using a stardust dragon or another damage type the Avenger emblem is a better option.
And Celestial Shell, it is an unusual choice but not a bad one, it gives a bit of everything which might be what you want, but if you feel like replacing one you should replace this one. If you want a protective accessory I recommend the Frozen Shield, it makes you immune to knockback and makes you take 1/4 less damage when you are below half of your health.
Good luck! Your accessories are fairly good right now, remember that you might also need to make a better arena or prepare better potions in order to win, your gear is not the only thing that makes you win