Hard to say.
Starbreaker was completely unfazed by an assault from Silver Age Superman(along with the rest of the Silver Age JLA, for that matter) before casually owning him with a concentrated blast of red solar radiation(which is one of Prime's only weaknesses):
https://i.imgur.com/T70sC3M.jpg
https://i.imgur.com/r96zc4Q.jpg
*Yes, that appearance is still canon to him, as it was explicitly referenced(and outright shown) in some of his later/post-crisis appearances.
Starbreaker is also an energy vampire. Even though his preference is the energy of stars(which makes sense given that he is an evolved Sun-Eater), he can still absorb nearly any type of energy he comes in contact with...
The energy of 3 stars:
https://i.imgur.com/1ZyCWgI.jpg
The energy of the Darkstars(team):
https://i.imgur.com/XwJLZE2.jpg
https://i.imgur.com/iW523oD.jpg
Firestorm and Doctor Light's blast:
https://i.imgur.com/R04WEP2.jpg
https://i.imgur.com/Z21RpBh.jpg
https://i.imgur.com/Kuk4yNc.jpg
https://i.imgur.com/gZ5uSrL.jpg
*Note that Light had a direct connection to Vega(the star), and in only ONE panel 'breaker's absorption took 100 million years off its lifespan. Crazy.
...He even absorbed Vixen's energies, which are esoteric as f*ck:
https://i.imgur.com/JeuaLXi.jpg
https://i.imgur.com/rwtQ5ZO.jpg
At the very least that trick would come in handy against Prime's HV, but imagine if 'breaker could pull the Guardian's power(or even the solar energy in his cells) from him... Damn.
