so in the game's legend of Zelda, there is the Zora armor. it helps you swim faster (which is shown by having flippers on the feet so obviously that would help, and it's skin-tight to fit whoever it was made for) and it lets you do the impossible; swim up waterfalls. how could you make something like armor, that can help you go up waterfalls? it sounds impossible and purely based on the magic in the game, but I feel like it could be done considering that waterfall climbing fish exist. it doesn't even have to fit the description or look of Zora armor, it just has to be some type of armor.
There's a kind of goby that is able to climb waterfalls by attaching it's abdominal sucker to the slick wall behind the waterfall as well as it's sucker-like mouth to move in a fashion similar to rock climbing in order to slowly move up the waterfall. So it could have a kind of sucker or otherwise sticky surface on the chest, with perhaps suckers on the hands, which, with the proper strength, could allow someone to climb up a waterfall. Though it may require a little hand-waiving. The flippers would absolutely help with climbing up waterfalls as well, as they help push more water as you switch where your suckers are. The armor could also be better streamlined and allow the water to flow by it more easily so it's easier to go faster. Likely it would have some kind of face protection due to all the rushing water. But other than that the amount of actual protection would vary with materials. Any metal would likely have to be a kind that doesn't rust with water, and cloth shouldn't be very absorbent.
If you want it to look more like the Zora armor in game, the metal on the forearms and shins could contain some kind of jet in them that takes water in and shoves it out even faster than it was going. However the pauldrons(shoulder armor) seem like they would get in the way more than help. But they do add protection, even if they would be heavy.
I made a visual representation of how the movement for pulling oneself up the waterfall could work to help visualize. The red is when the chest sucker is down and wouldn't move, the blue is when the hand suckers are down and wouldn't move. The back fins aren't moving in this due to the fact they are the easiest to visualize, they just go up and down like they usually would while swimming.