I found that taking one of those 3M "Between coats finishing pads" (replaces "00" steel wool) with some soap and water helps to clean off the grime of aged horn without taking the "age" out of it. If you rub too hard or too long though I think it might take that aged look out off.

Not sure if you can tell from the pictures but It seems to have made a difference.






I think some renaissance wax after this oughta be just fine.