How did this work out? How powerful is this talent?
Oh, well, on one hand, it's quite powerful (
but not for the double-target part and more for the fact it doubles the radii of the areas of effect) but OTOH most "important" mages have it so it's almost a staple of being a mage and willing to become powerful, making it relatively less powerful (I mean, if
any and all mage of importance has it, it's a normal thing with which to deal and it's the "normal" way mages and magic are, at some level). Of course, it being a talent determined at "birth", meaning a birth gift, that "most important mages have it" implies that you have little chance becoming powerful if you don't have the talent (implying it
is a powerful talent) but, well, it's like saying that being highly intelligent makes it easier in life to become someone of importance. It's true but it doesn't mean much more than being intelligent is a plus in life because, all in all, there are a lot of intelligent people.
In a nutshell, it's an interesting talent that makes the one who is gifted with it more likely to become powerful, but the actual "power" of the talent only depends on how rare you make it to be. If only one person out of a billion has it, it's incredibly powerful. If one person out of a million has it, it's powerful enough to be noticeable. If you go by the RoCo I, you have 1% on the magic abilities table to obtain it. Even by extrapolating on the other other tables, if one person out of a thousand has it, it's merely a talent that gives you a plus in life.
Diected spell OB also tends to be lower than weapon OB's. Since a fighter can get a second attack for a -20 mod (with TWC), why not the spell user?
Ah, but weapon OB is a comparative skill (the opponent can lower your score with his own weapon score, i.e. "parry"; as your OB increases, so does your opponent's) whilst the DS OB is an absolute skill (there's no skill to lower yours, only magical ways that just don't increase as fast). In other words, in general, your melee OB isn't much higher than what your opponent can oppose you (through parrying) so lowering it by 20 may be a dilemma. OTOH, your DS OB can quickly exceed by a large margin the penalties your opponent can give you (because, aside from magical ways, they remain constant) so lowering it by 20 is quickly not a big deal.