"Ulysses uses a unique non-player version of the weapon.. There are 4 different versions depending on the players level, making it the only weapons scaled to the players level, each has a 10% chance of knockdown" from the wikia.

Is the weapon you obtain at the end of the questline scaled to your level, or is it just his version?

I'm guessing (and I hope) it's just his version that's scaled, and you obtain the same weapon regardless of level.

His.

Good, this weapon is going to be stupidly strong when I'm perked up.

80 base critical damage, boosted by various perks to over 300%, going to be deadly.

It's insanely powerful. I fought the Legendary DC the other day, and took off over 60% of his health bar with one Grand Slam in VATS. Granted, I was full of drugs and perked into crits pretty heavily, but impressive nonetheless.