His AP is comparable to her Dura, so "she can tank artillery shells" is never a good counterargument, she won't be one shot but she(and her rigging) will be damage and he can make them sharp to penetrate her as well. The gif of him struggling to make those ice is anime only, in the manga he created those same ice with a mere casual lift of his hand as a show of power, the gif was more of a evidence for how big his ice can get, which is consistent since throughout the battle he has to constantly move and create large quantity of ice quickly to counter dabi huge flame, who need no charge up for his moves, if it took him that long to create those ice, dabi would've torched him long ago. And yes against a comparable opponents, stamina would matter a lot, to say that it doesn't is ridiculous. If 2 7B characters of similar AP fight, the one with the higher stamina will be more likely to prevail, and hers is already lower than his and will only get weaker with damage to her rigging which we established that he can do especially with her highly inconsistent shields. And you seem to think that geten ice spike is somehow a sneak attack that she can counter, no there're not, geten freeze the water then create upwards facing spikes out of them on a wide scale, he won't be sneakily poking her with them, he'll turn the entire canal into a massive spike field like the link I provided, and prinz can't outrun it due to its range and speed. Again she may have experience with danmaku but never one with such size, one that can change direction or reform if broken, while simultaneously making sure the ground doesn't penetrate her. Geten will have full environmental control by freeing and controlling the water which mean prinz mobility will be highly limited in addition to constantly dealing with his aforementioned attacks while geten will have free range to float around and defend himself. If she focuses on attacking him then she'll be hit from all angles which her shield cannot block, if she focuses on defending then it's only a matter of time before she run out of stamina. This is all assuming she's constantly fighting in tip top condition but she wont, she'll be hit or cut here and there, her shield could failed to activate or be overwhelmed, her rigging could get damaged, all of this is making an already slippery slope more and more icy. It isn't that she don't have any wincon or be completely helpless but compare to his higher stamina and LS, the size and relentlessness of his attacks, his more numerous, reliable and renewable defenses and most importantly his full and absolute control over the battlefield due to the fact they are fighting in a canal and not in a city where limited supply of water, streets and buildings can hinder him. Overall, prinz will hang on due to her versatility and intelligence but in the end she'll soon find out that this is a difficult and drawn out fight that is more likely to end in her defeat with an ice cold prison that she can't escape