I would not recommend using ironwood, kamagong or any hardwood sticks when doing stick on stick drills. Hardwood sticks shatter when they break potentially having a jagged piece flying through the air. I use my kamagong sticks for condiditioning and work in the air. (they are certainly what I would use in real combat though I probably would choose my ASP expandable baton first)
Rattan is an almost perfect training stick in that it very rarely shatters and instead splinters. It has great vibrational dissipation and that also helps save wear and tear on your hands, wrists and forearms. Plus once they start to fray you can tape them and they will be usuable for years to come. I personally use renfro cloth hockey tape. It is slightly abrasive on the hands the first few times you practice with them but that goes away quickly. The cloth absorbs the sweat and the sticks are not slippery in your hands. I have done this for a long, long, long time and I literally have tons of sticks. I woud stay away from electricians tape, duct tape, etc as they get slippery and that is something that just is not needed when training. Hope that helps.