I like Gerhard's suggestion as to why Christ is called "Christ" that is, "anointed." He states that whereas the mediators of the OT were anointed with literal oil, Christ's humanity is anointed by both the Holy Spirit (the mediator of the Incarnation) and also the fullness of divine glory (genus majestaticum). He of course cites Psalm 45, which is cited and applied to Christ in Hebrews 1. I'm very fond of that text and used it at my wedding: "You have been anointed above your brothers with the oil of gladness."
Anyways, I don't think that Gerhard is engaging in fanciful typology here. Remember, the point of anointing people with oil in the OT was to imitate the divine glory. "Kavod" does quite literally means to "shine" or "glow" (among other things). The mediators represented the covenants which bound God and humanity together. Hence they represented both parties. The glow makes them resemble God's hypostatized glory, which we know from the NT is the pre-incarnate Christ and his self-donating presence with Israel in the Temple. This presence represented divine solidarity with Israel by his literally giving himself to them. It prefigured the Lord's Supper, wherein God again donates himself to us as a sign of his love and forgiveness.
The mediators represent this solidarity as well. Not only should be look to the oil, but one can also see this phenomenon in the golden clothing of the high priest. One can also point to the glowing face of Moses in Exodus 33.
Ultimately, Christ shows himself to be superior to the mediators of the OT. Not only is his glory double, in that he is anointed twice (with the Spirit and his own divine attributes), but he also is the true God and the true man. By contrast, the mediators of the OT merely represented them. Theirs was but a shadowy glory, where Christ is God's kavod come in the flesh. He also to the only authentic human being.