Anything that doesn't hurt will flex too much or have padding that will be too thick to cut through the air. I've tried every sort of practice stick, and the best I found was a Sonny Umpad design with a nylon sign 1/4" post at the core, covered by thin foam and some sort of electrical heat shrink tubing. They were good for a while, although quite whippy and unsuitable for blocks. There have been many types of sticks, but you really want a thinner rattan 5/8" x 25-28" is good. If the stick is longer, it is whippy. Then, wrap the stick with pipe insulation foam from Home Depot. The tube will need a skin, and again, I bought a bunch of nylon sleeves from Nick at bloodsport.com along with the 5/8" sticks. The 4 oz. MMA gloves (make sure yours doesn't have that stupid bar in the palm) are unobstrusive for sparring and stickwork, though they do nothing to protect the thumb, which is most often damaged when strikes the thumbnail from the tip side. Over time, I have found that the sticks last about twice as long as the foam. More often, the nylon case breaks at the tip or the foam at the tip slides down to expose the stick, so check the tips of the sticks before each round.
In the interest of eye protection, I'd invest in some fencing or WEKAF masks. Eye damage is only a matter of time. Fencing masks are probably better as they protect more of your head and have no major gaps as can be found in the WEKAF gear. WEKAF helmets are better for breathing and need less light, though that solid grill is harder on sticks and the ears. And if none of your players have been hit in the eye during years of practice, the sparring is, uh, well, "too controlled." I truly believe that you need to hit the head, face and legs and swing harder to practice eskrima effectively.
