The pointy trident was perfectly suited to taking advantage of the Probe's main weakness: if you pierce the crunchy outside, it goes BOOM.
On top of that, this was at the time Aquaman's death scene. And he was naturally overperforming as a result. The dramatic needs of a narrative trump all.
Aquaman with this gear is not favored vs. pre- or post-reboot Diana, in or out of water, and with or without her bracers. Of course if Diana is somehow a Big Bad, and Arthur is going to die to win, he might well get the victory.
