note: since it is crafted, the sabre is created at the same level as the crafter.
so, it is more powerful at higher levels.
also, it has the highest raw damage of anything short of tenebrium (about 20% higher than a normal sword of average quality of the same level). you can find more damaging weapons though, if you get rares/legendaries with good elemental damage on them.
both the buffalo headpiece and the blade are completely random unique drops. I found mine in a friggen haystack near some pigs in Cyseal at level 4.
all that said, as a unique it lacks a bit of "oomph" compared to some of the other uniquest. the damage is decent, but with only 1 point of strength boost as the special, it pales to the specials on most of the other unique weapons. I thought a modder might do well to add something like "gives skill: battering ram" to the completed sword.
don't kill yourself trying to put it together, unless you want to make it some sort of treasure hunt for yourself.
I've seen the blade for sale at both the quartermaster and from the legionnaire captain (Aureus). more commonly from Aureus, but only at level 7 and above.