The AAM medallion he would have would have been tied to Dragon Moon, which has been destroyed. Therefore, he will need a suitable power source for it. Such a power source could be found on planets that have had magic races living on it for a very long time, IE an already established magical empire, or by utilizing an exceedingly powerful crystalline energy core, such as the one the new AAM jewelry utilizes on the Ancient Relorian Megalith.
Also, don't you think 20 animites would be a bit much?
A longer sword grip wouldn't do anything for him unless he sometimes uses two hands with the longsword. But then, it wouldn't be a longsword anymore due to the extended hilt. It would be called a bastard sword, AKA hand-and-a-half sword. Not only that, but a bastard sword would be quite detrimental to that kind of combat style. Getting in close with your opponent while you use a longer weapon puts you at a disadvantage because you will be more limited in your range of motion with your weapon. Instead, for in-your-face fighting like Hiren's, you'd be better off with a shortsword.
And the usual armament for a Diviae Relorian would be either a brigandine with mirror plates, scale mail, or full plate armor, a longsword, and either a large metal shield or a tower shield.
Also, since the Relorians would be wearing their armor, the only way he'd be able to buy differing Relorian armors would be to buy armor that no longer fits the previous owner, so it would most likely not fit Hiren. Either that, or he could simply make the armor himself, since each Relorian Elite soldier is expected to do so anyway.
Besides, the only difference between the armor is what it's made of. Shamai is usually leather and bone, Diviae is mostly a silver alloy, and Arcana is usually cloth and crystalline plates.