NOTE: Death Chargers Reins is not bugged on all servers, but it was bugged on the repack that I use but I fixed it. If it is not working on (AKA when you use it instead of it mounting you on the death charger it mounts you on a normal skeletal horse or a fiery warhorse) your server then use this guide and it should be working.
Open up Navicat and go to creature_names and go to entry 11195. Go to displayid and change it to 10718 and restart your server. Its that simple. If you have any problems with it post here and I will try to help