From all the offscreen activities/fights involving Whang Zhi. This dude seems to be legit powerful figure slightly below the OG Yonko by portrayal.
Probably Silver Axe, i think at least one of the Rocks members will try to get back at Hachinosu trying to claim the island after Xebec death/crew disband.
I bet it's Silver Axe as the guy doesn't appear in the panel with them, Zhi might have killed Silver Axe after a war broke out when he comes back to claim Beehive.
At least give a scar on him, as an implication of fierced death battle.