Shard O'Glase said:
specialization +2 to ever attack with the weapon your likely using almsot every round or a +4-6ish to one round of attacks a few times a day.
Don't forget that specialization binds you to a single weapon type. A paladin has little that binds him to one sort of weapon, and this power works with every weapon he uses (e.g. his melee weapon and his ranged weapon, or his sword as default weapon and his cudgel against the undead, or for the axe he found and that replaces his morningstar, which is inferior to the axe).
Also, as the character gains ever more charisma, the feat gets better and better, giving more damage in more rounds (and, as specialization, with more attacks per round).
Seems to be a bad feat to me in the intended number of fights per day campaign.
I dare you to point me to the place in the core rules where they say what number of fights is intended for your average campaign. I'm sure you won't find such a thing.
The CR System might imply something like that, though. According to the CR system, you can fight 4 "challenging" fights per day (and the 5th may well be fatal). Let's say they last an average of 3 rounds, and we have an average of 12 rounds of fighting per day. There might be less fights, because you get to hit a big guy, but this will probably take you longer, so it evens out. With easier fights, you will probably not need the extra damage anyway, or the fights are really short, so oth cases won't change the number of rounds significantly (I won't enter the demiplane of mathematics on this one, though).
Your average paladin will have at least Cha 18 (15 or 16 base, put one point in at 4th, and +2 from Item) when he gets the feat. This means that you get +4 to your damage rolls in 7 out of 12 rounds each day. Slightly more than you get from weapon specialization (2 attacks/round, 12 rounds, 2 points damage = 48 for power attack; 2 attacks/round, 7 rounds, 4 points of damage = 56 for divine might)
On level 12, a fighter will have greater weapon specialization, so he gets +6 with two feats, in 12 rounds. The paladin will have Cha 22 (15 or 16 base, 3 points for level-ups, and +4 from an item), and his second feat for this will be extra turning. So he gets +6 on every of his three attacks (like the fighter) in 13/12 rounds. So it is, FWIW, the same. Improved Weapon Focus might help the fighter hit petter, but the paladin will be able to raise his Cha even higher, so this will grant him even more power than greater weapon specialization.
The real hitter with this feat isn't the paladin or the cleric. It's the blackguard. This guy will probably have weapon specialization (and if you make a ftr/blk built instead the common ftr/rog/blk, even greater specialization) and this feat. That's scary.
In a game with a few big fights per day it may be ok,
Dungeon Crawls are not the norm. I actually see it often that the party has only a couple of fights.
or if you are built around this one feat and have an absurd CHR it will be good but your character will be overall subpar in a fight.
High charisma is never absurd for a paladin, and he hasn't to built the character around this feat either. He really only has to spend a single feat for this (power attack is almost a natural choice for paladins, which are heavy hitters) and the high charisma is normal for him. Of course the fighter will be better in combat, but he's supposed to.