Some thoughts I have
Class Role: Leader/Striker (Relic Hunter) or Leader/Defender (Explorer)
Replace Streetwise with Nature: You are more apt to need to know how to survive and find your way to the lost temple rather than carouse in the local pub.
Master of your Trade: The Historians advanced education give them an edge in surviving regardless what life throws at them. You gain a +2 bonus to all knowledge checks.
Slough Off Mark: This ability isn't work taking a mark penalizes you when you attack a target other then the one who marked you, this ability removes a mark the target has in you. I don't see any benefit.
I agree with Eric n the fact that you need to come up with multiple build options.
Relic Hunter: Focused on having a high Intelligence, using your intellect to locate weakness in your opponent and exploit it. Give them
Careful study: you study your opponent's movements and identify a weakness. When you are ready, you can inflict deadly blows with ease.
As a minor action in combat you may study a creature. Make an appropriate knowledge skill depending on the creature Dc 15, success means you have studied the target. Failure means you can retry with another minor action. The DC increases to 25 for monsters at the paragon level and 30 for those at the epic level.
Once per round when you deal damage to a creature you have successfully studied, add 1d6 to the damage. This amount increases to 2d6 at 11th level and 3d6 at 21st level.
Explorer: You focus on your insight and perception to control the opponent forcing them to attack you or compromise their defenses. Give them
Insightful Defense -By spending a minor action you size up your opponent anticipating his moves before he makes them.
Choose an adjacent enemy, that enemy is marked as long as you engage it. Additionally, you get a bonus to OAs against the marked target equal to 1/2 your wisdom modifier and whenever the marked target shifts any number of squares you may shift that many squares or up to 1/2 your wisdom modifier (whichever is fewer) as long as you end your movement adjacent to the marked target. Add 1 square to the number of squares you shift at 11th level, and add a further 1 square (total of 2) at 21st level.
Make one Encounter Exploit of each level geared towards each build
(abiliteslisted above are from other post which i feel work with this class)