Well I did, I defeated Heolstor and all the normal bosses as solo Guardian. He wasnt hard, Adel gave me way more trouble, and if he anything Heolstor felt like a "stamina" check, how many hits you can block and have leftover stamina to do a guard counter, very similar to BBH and Crucible Knights. Glad I Staminamaxxed.

I still dont know if I have it in me to solo birb everdark bosses, giga Adel terrifies me and giga Libra seems actual cancer to fight as Guardianb