BRD's set bonus is actually great, compared to a lot of set bonuses:
THF:
"Occasionally" increases damage of 2nd/3rd hit of triple attack.
DNC:
"Occasionally" doubles damage when you have a samba up, unclear if party members get this bonus.
NIN:
"Occasional" extra attacks while dual wielding.
WHM:
"Occasional" nullification effect from barspells.
BST/DRG/PUP/DRK:
"Occasionally" increases damage in direct proportion to your pet/wyvern/automaton/own HP (so if it is at 100%, doubles your damage)
SCH:
"Occasional" quick magic effect.
SAM:
"Occasional" double damage on Zanshin.
BLM/SMN
"Occasional" boost to damage proportional to twice the percentage of MP conserved if conserve MP/Blood Boon are triggered.
MNK:
"Occasional" second kick attack per round without the use of footwork.
PLD:
"Occasionally" absorbs damage taken.
RNG:
"Occasional" double damage when rapid shot triggers.
COR:
"Occasional" triple damage quick draws.
WAR:
"Occasional" double damage double attacks.
BLU:
"Occasional" ***.
All of these are pretty MEH when you look at their proc rates (all low). Then you get to RDM, which always lets you increase the duration of buffs on your party members when Composure is up (not too shabby), and BRD which always gives a +attribute bonus to your songs.
BRD is in the game with RDM in that the boost ALWAYS applies, so I think it's actually one of the better ones :)
EDIT: OOps, necro bump. For some reason I didn't notice the posting date o_O