Dryblades can appear as rustic paddles or a matched set of oars of various lengths (rowboat, longship, or galley). Woodworkers make them from the wood of specific trees that grow in arid and secluded locations, and have them consecrated by water spirits or Wavespeakers. They remain remarkably dry in all conditions, even when submerged.
Dryblades repel water so well, they effectively double the surface area of the physical paddle or oar blade when inserted into water. When a water craft has Dryblades as at least 75% of their complement of oars, the speed of the craft doubles. A single set will allow a rowboat to row upstream in a typical river current, and a galley or longship outfitted with Dryblades will speed past a similar ship under full sail in all but strong winds.
Dryblades' hydrophobic properties do not make them significantly more buoyant than regular oars or paddles, though they will retain an envelope of air around them when submerged from the surface. This pocket of air will foul in mere minutes if used as an oxygen supply underwater.
Since Dryblades never get wet, they can't be sealed as normal oars would. The wood dries out and becomes brittle in a remarkably short amount of time, so Dryblades remain in high demand among those who know about them. The woodworkers who know about the drywood groves jealously keep the secret location to themselves, even in death.
Stories still circulate of the Waterstrider Wizard who tied a pair of Dryblades to their feet, secured them with an Arcane Lock and decided to walk across the mouth of the Whitewind River. The wizard had prepared Knock to release the ties in an emergency, but when they flipped upside down in the churning waters, they apparently couldn't spit out the verbal component correctly. Rumor has it the Twinblade Corsairs looted the body a mile off the coast, and now they have the fastest launch in the Malachite Archipelago.
Prompt: Blade, #5 in the 31-part Dicember 2021 challenge, as created by Brian Bird and promoted by Dyson Logos. Wombat's Dicember 2021 List of Posts. I wanted to use a less obvious meaning of blade for this one.