The acid has eaten microscopic holes and grooves in the steel … that is what an etch is. You need to rinse the FC off the blade, wash it well to remove loose oxides, and then neutralize any remaining acids. Windex, ammonia, or TSP all work. Don't spare the neutralizer … spray it on, scrub it in, rinse it off with hot water … and repeat.
Now that the blade is very clean and acid free, it has moisture in those holes and grooves. You need to dry it well with paper towels, and the evaporate the trapped moisture. 30 minutes in a 250F oven will do it nicely. You need to do that pretty soon after drying the blades. Other methods are to set the blades in a very warm spot near the forge or other hot place. Once completely dry, oil immediately while still warm. That will draw the oil into the holes and grooves. If you live in a very humid place, after working the blade for the day, apply a new coat of oil. In normal climates, you can set the blade in a dry place between sanding/grinding sessions.
