I see what you are trying to get at but the Arbiter is not a singular character, there have been multiple Arbiter's; 192 or something like that. On the other hand Thel' Vadam is a unique character who took a active role in war even before he became the Arbiter.
@pyromaniac: @Make_Me_Mad: @Skilbs: @Azteck: I absolutely agree that there should be a concept page for the Arbiter as a rank, but it should also be noted that both the character pages entitled Thel 'Vadam and The Arbiter refer to Thel 'Vadam, The Arbiter character page does not refer directly to the rank. The way I saw it, it made the most sense to delete the Thel 'Vadam page as The Arbiter page has all the information that the Thel 'Vadam page does and more. Whether or not The Arbiter's page should be renamed to Thel 'Vadam is another issue.