The problem with them is when you start to get magic weapons it is damn costly to mantain them on par with, let's say, the two-handed-fighter greatsword, as you will need more than one throwing axe or dagger. Or if you want to have only one weapon (chakram is a good one for this) there's the magical ability tax Returning, and even then you are restricted to one throw per turn, as the weapon returns only before your next turn.
I think the throwing fighter is very cool concept, but they get no love from rules. D&D4e kind of fixed it: any magical throwing weapon get the returning ability for free. I think it's a very fair change, and made me think about these houserules:
Magic Throwing Weapons: Any throwing weapon that have at least a +1 enhancement bonus flies through the air back to the creature that threw it. It returns to the thrower just before the creature’s next turn (and is therefore ready to use again in that turn). Catching a throwing weapon when it comes back is a free action. If the character can’t catch it, or if the character has moved since throwing it, the weapon drops to the ground in the square from which it was thrown.
New Weapon Special Ability:
Returning: This special ability can only be placed on a weapon that can be thrown. A returning weapon teleport backs to the user's grasps as soon as the weapon hits (or misses) it's target, making it ready for use immediately, therefore allowing a full attack action with it. As the returning weapon is teleporting, and not flying back to the user it appears in the user's grasp even if he has moved after thrown it.
Moderate conjuration; CL 13th; Craft Magic Arms and Armor; instant summons; Price +1 bonus.
So, now you can have viable weapons for your throwing fighter. Either as a set of four +1 Flaming/Frost/Shocking/Thundering starknife or as a +1 Holy Returning Chakram.
Comments? It's balanced?
While I am loathe to admit it, this is a good idea for Throwing Magical Weapons, as it makes them quite valuable to the average player, rather than the very 'focused' player who is aiming for a very specific Throwing-Type PC.
I do like that Throwing Enchantment increases this to be an instant-return weapon, meaning that a Fighter can theoretically throw the same dagger at any number of targets, but I would increase this to a +2 or even a +3 Enchantment.
Reasons:
1) The throwing weapon becomes extremely versatile, more so than a Melee weapon or a dedicated Ranged weapon. A Fighter, or any other 'high BAB' character who invests in a Returning Weapon can basically throw the dagger at a distant target, hold up his hand as the weapon re-appears then shank the guy trying to flank him, then throw it at the distant target again.
2) The throwing weapon should gain the ability to teleport back to the wielder a number of times per round equal to it's enhancement bonus. This might seem limiting, but dropping the Throwing Enchantment back down to 1 makes this a much more balanced option, and also encourages the player to have more than one single 'uber-weapon'. It also helps stop Monk Shenanigans who then turn around and sodomise the PC with his own toy.
+1 to both posts above. Me likey.
Feedback
Thank you. My first though was to make the insta-return valid only in the first increment of distance. Maybe this way is more balanced, and with less bookkeep. My fear is that may make the ability fairly useless...
Well, thinking about it, maybe x number of returning per round is better...
dotted for future reference.
This is basically how all magic thrown weapons work in 4e. If it's magic, it returns. All of them return as soon as the attack resolves. If you can make multiple attacks in a round with a ranged weapon, you can use the same thrown magic weapon to make all of them. If you have to use a main hand and off hand weapon, then you have to have two magic weapons. But that's not hard to get in 4e.
This is one of the things I like about 4e, even though it does sometimes feel a little too cheesy.