I did mine this past spring...
I picked up some rust converting black from PepBoys
(Cant remember the brand - Rustoleum, Krylon, cant remember, I will have to update the post later on when I find it)
Only one arm was REALLY bad with flaking paint chips and light rust spots, the other one had only faded. But I wanted to make them look uniform - so I treated them equally.
First I used a wire brush to get any loose bits off, wiped them down and let them dry about a half hour.
Then I took the rattle can to them for 3 or 4 coats (at the minimum wait time recommended on the can)
Next morning I put them back on. Looked like brand new... they still look great.
Tip - before unbolting the arms - I took a blue sharpie to the bolt head and a spot inside the arm. I made a small line to realign them later.
Oh, Don't forget to spray the little bolt cover cap too, so everything matches.
~ ~ ~
Van Eyes - slightly trimmed, Sylvania SilverStar ULTRA head lamps, Red (port) & green (starboard) 5 LED 'headlight horn' lights, PIAA silicone windshield wipers, K&N Filtercharger (in stock air box), MacNeil WeatherFlectors, Assorted cargo nets from previous vehicles, Optima red-top battery, Transmission Interceptor, 20 LED 'light tower' turn signals & brake lights, 18W PIAA W2 running lights, Trooper skid plates, Black Luverne step bars w/Tone's custom brackets