If the warlord is weakened, blinded, marked by another creature, or in some other way, shape, or form, has attack/damage penalties, it's a good power to have.
There may be other obscure beneficial conditions, like you are fighting a fire elemental that does damage if you attack it, but your Tiefling rogue doesn't care so much about the heat, so you give him an extra attack. Or an allie may have a cold based basic melee attack that the fire elemental is vulnerable to, and it may be beneficial to give him an extra attack.
But generally if the Warlord is in melee range of something, there is probably some better at-will ability that does something better than granting a basic melee attack to an ally. Remember things like sneak attack and hunter's quarry can only be used once per round (though warlock's curse seems to work all the time). So you don't get as much bang out of such abilities when attacking out of turn, or gaining second attacks with action points.
Not a bad ability, just somewhat situational to use.
There may be other obscure beneficial conditions, like you are fighting a fire elemental that does damage if you attack it, but your Tiefling rogue doesn't care so much about the heat, so you give him an extra attack. Or an allie may have a cold based basic melee attack that the fire elemental is vulnerable to, and it may be beneficial to give him an extra attack.
But generally if the Warlord is in melee range of something, there is probably some better at-will ability that does something better than granting a basic melee attack to an ally. Remember things like sneak attack and hunter's quarry can only be used once per round (though warlock's curse seems to work all the time). So you don't get as much bang out of such abilities when attacking out of turn, or gaining second attacks with action points.
Not a bad ability, just somewhat situational to use.