Aquaman's Costume: An In-Depth Look
The Tattoos and Armor Design
Over at Screen Rant, they've got a look at the historical and cultural significance of the tattoos and the "scales' on his armor designs.
The basics?
Those tattoos on his hands likely are the mouths of Tiki gods, indicating Arthur's role as a provider for his people.
The shoulders -- both his tattoos and the armor design, feature stylized spearhead imagery common to Polynesian culture. Elsewhere on his torso and wrists, there's similar recurring shark's teeth imagery. In both cases, it ties to previous remarks by the actor that they hoped to make Aquaman an embodiment of island culture.