What you really, really want is the bloodstorm blade prestige class from Tome of Battle. That class offers this class feature at 4th level:
Lightning Ricochet (Ex): From 4th level on, you can throw your weapon at a nearby foe and command it to immediately bounce back to your grasp. Any time you make a ranged attack with a thrown weapon on your turn, the weapon immediately returns to you, and you can catch it as a free action. This ability allows you to make a full attack entirely with thrown weapon attacks, or a mix of thrown and melee attacks.
There is no way to get this feature in item or feat form. If you can back-port Pathfinder material, the blinkback belt does it, and is an excellent choice, but that is not 3.5e material.
Also worth noting, the same prestige class offers thunderous throw at 2nd, which allows you to treat your thrown-weapon attacks as melee (allowing you to use Strength, Power Attack, etc. etc.), which can be really potent. The rest of the class is pretty much meh, but four levels is all-but-mandatory for a thrown weapon character, particularly one who wishes to use a warhammer rather than shuriken or similar.
These benefits also synergize really nicely with hammer of Moradin: since your throws are treated as melee attacks, powerful grip applies to these attacks, and then you can use power throw to attack a whole line of people, gaining pretty large damage bonuses, several times a round. That’s pretty nice, and totally makes up for the fact that hammer return is redundant with lightning ricochet.
But despite that, please note that it is all-but-impossible to keep an epic-level game functional, and martial characters in particular have almost-zero ability to retain relevance in the face of competent use of epic magic, particularly Epic Spellcasting. In fact, D&D 3.5e has so much difficulty with increasing level that many games actually stop at 6th (see E6), because even as early as 7th these problems get to be pretty severe. This character may struggle massively to contribute much in a campaign so high-level. Frankly, the campaign as a whole may struggle mightily just to remain coherent.