It was definitly a buff. Soul Arrow went from 70ish to 90ish damage on the enemies just outside Firelink. But yeah, it wasn't a very big one, and is way too little. Frankly, sorcery (and probably miracles too, but I haven't spent much at all time with them yet) just needs a complete overhaul in this game.
There's just too many problems, from the joke that is the damage, to the "speed" of the spells (boy is that a misnomer) coupled with the true speed and hyper aggressiveness of most enemies, to the at times insane, and generally unsustainable even with ash flasks fp costs, to the piss poor and likely not even functioning scaling on several staves.
That's not even mentioning that it takes 3 rings and a headpiece (which lowers your magic resistance significantly, on top of the extra magic damage you take from one of those rings), AND a minimum of 50 int to even get to a point where you CAN start reliably killing things without chugging ashen estus between every other kill. Imagine how it would be if you needed 50 str or 50 dex to start seeing some kind of damage on your weapons? Because that's pretty much how it is with Int (and possibly miracles).
Frankly, sorcery is just broken.