Plus, it has a limited returning ability. It only works if you miss, but it is a nice little option for lower level throwers on a budget.
Which books are the boomerangs in?
The two feats are found in Races of Eberron, as has been pointed out. The boomerangs themselves are from the Eberron Campaign Setting Equipment section.
BOOMERANG DAZE
You can daze the targets of your boomerang attacks.
Prerequisites: Proficiency with Talenta boomerang
or Xen’drik boomerang, base attack bonus +4.
Benefit: When you attack with a Talenta boomerang
or Xen’drik boomerang (see page 119 of the EBERRON
Campaign Setting), any target creature that takes damage
must succeed on a Fortitude save (DC 10 + damage
dealt) or be dazed for 1 round (until just before your
next action). If you have the Boomerang Ricochet feat
(see below), you can daze both targets.
Special: A halfling fighter from the Talenta Plains
or a drow fighter from Xen’drik can select Boomerang
Daze as one of his fighter bonus feats.
BOOMERANG RICOCHET
You can strike up to two foes with a single boomerang
throw.
Prerequisites: Dex 13, proficiency with Talenta
boomerang or Xen’drik boomerang, base attack
bonus +4.
Benefit: You can hurl a Talenta boomerang or Xen’drik
boomerang (see page 119 of the EBERRON Campaign Setting)
in such a way that it ricochets off one target to strike a
second target of your choice. If your initial attack hits,
you immediately make a second attack roll at a –2 penalty
against any target adjacent to the original target.
If the first target is hit by a sneak attack with a
boomerang under the effect of this feat, the second
target is not also vulnerable to a sneak attack on
the ricochet.
Special: A halfling fighter from the Talenta Plains
or a drow fighter from Xen’drik can select Boomerang
Ricochet as one of his fighter bonus feats.
DROW SKIRMISHER [RACIAL]
Your experience with the guerrilla-style combat of
the deep jungle grants you mastery of the weapons
of the drow.
Prerequisites: Drow, region of origin Xen’drik
Benefit: You treat the Xen’drik boomerang†, the
drow scorpion chain*, and the drow long knife* as
martial weapons. As well, you gain a +1 bonus on damage
rolls when making an attack with a drow long
knife or a drow scorpion chain as long as you
have moved more than 5 feet under
your own power during
the round in
which you make
the attack. For
example, being
bull rushed 10
feet isn’t sufficient
to grant
you the extra
damage from
this feat.
If you have
any of the following
feats
for the dagger
or short
sword, you
can apply
the feats’
effects to
the drow
long knife:
Improved
Critical,
Weapon Focus,
Weapon Specialization,
Greater Weapon Focus, or
Greater Weapon Specialization.
If you have any of the
same feats for the spiked chain, you can apply the
feats’ effects to the drow scorpion chain.
Additionally, when you spend an action point to
influence an attack roll made with either a Xen’drik
boomerang, drow scorpion chain, or drow long knife,
you also add the result of the action point roll to your
damage for that attack.
† See page 119 of the EBERRON Campaign Setting.
*New weapons described in Chapter 8 of this book.
TALENTA WARRIOR [RACIAL]
You have trained with the ancestral weapons of the
Talenta halflings and are particularly adept at striking
from the back of a dinosaur mount.
Prerequisites: Halfling, region of origin Talenta
Plains.
Benefit: You treat the Talenta sharrash, the Talenta
tangat, and the Talenta boomerang (see page 119 of the
EBERRON Campaign Setting) as martial weapons; you gain
a +1 bonus on damage rolls with any of those weapons
while mounted. If you have any of the following feats
for the Talenta sharrash, Talenta tangat, or Talenta
boomerang, you can apply the feats’ effects to all three
weapons: Improved Critical, Weapon Focus, Weapon
Specialization, Greater Weapon Focus, or Greater
Weapon Specialization.
Additionally, when you spend an action point to
influence an attack roll made with either a Talenta
sharrash, Talenta tangat, or Talenta boomerang, you also
add the result of the action point roll to your damage
for that attack.