Am DM'ing an Eberron campaign with 5th edition rules, and this subject has just become relevant, as the upcomming member of the party, is a Drow from Xen'drix.
This is what I've come up with so far.
Xen'drik Boomerang: Martial weapon for Drows, 1d6 damage (x3), range 20 / 50, bludgeon/piercing (higher damage due to the sharp edges).
Talenta Boomeran: Martial weapon for Halflings, 1d4 damage (x2), range 30 / 60, bludgeon (longer range due to simple yet elegant design).
On a missed attack, a boomerang returns to it's owner. Boomerangs are somewhat
Boomerang feat (name not settled):
+1 dexterity.
Pick either the Talenta Boomerang or the Xen'drik Boomerang to gain proficiency in.
On a successful hit, the boomerang returns to its user.
(Xen'drik boomerang special) Once per turn, on a successful hit with a boomerang weapon, you can attack a target adjacent to the hit target, as a bonus action. The boomerang does not return, when used in this way.
(Talenta boomerang special) Once per turn, on a successful hit with a boomerang weapon, the target must succeed on a Constitution Saving Throw against 8 + your professionsy bonus + your dexterity modifier, if failed the target has disadvantage on its first attack roll during its next turn. The boomerang does not return, when used in this way.
Thoughts: The talenta boomerang might seem a bit underpowered at first, but the +10 range really does a good difference, and the feat bonuses gives some tactical variation on the two types. A boomerang specialist, with both types in his arsenal, can really deal versatile destruction with these
Also, I have made them hard to come by, and carrying more than a few on you is impractiacl, which really balances the Return option for them, and makes it a hard choise to deliver the extra effect from the feat.