Wouldn't the Vibranium element prevent Flash's vibratory trick from working? That's part of what makes it so strong.
I agree with leonidis when it comes to who could do it with physical strength and say virtually no one.
I'd hold anything that happened to or was caused by Thanos weilding the IG suspect as he had total control over every aspect of this reality. Besides, I thought the Power Gem wasn't strictly for physical purposes but to boost the power of the other Infinity Gems. A downward smash with the thought 'Destroy!' in his mind and any of several gems could've caused the downfall of the shield. The reality gem could've caused it to radically destabilize, the space gem could've caused the molecular structure to separate, even the time gem could've returned the shield to a point in time before the alloy had completely set.
That's what being god is about though! 😛
The Saint of Killers guns could probly shoot through it, a really POed hulk could theoretically, the human torch might be able to melt it, the surfer could probably manipulate it, Galactus of course could break it, Superman Prime probly could, anyone above big G could, and any of the genius level intellects could probly find a way to break it, thats all I can think of right now....