User blog comment:RayShepp654/How to defeat the Reapers Theories/@comment-71.12.70.200-20101028191319/@comment-217683-20101028220339

Yeah... about that. Where are you getting that the leviathan is "bigger than any dreadnought"? The info we have actually suggests that the Leviathan of Dis is actually smaller than the dreadnoughts in use in 2163, twenty years before the first game. After all, it disappeared from the planet it was on after a batarian dreadnought passed through the system, a clear implication that the Leviathan was taken off-planet and out of the system by the dreadnought, likely in the dreadnought.

Nor is there any mention of weaponry or anything else that would make the Leviathan a "perfect weapon against the reapers[sic]". As for freeing it, remember that the Leviathan is believed to be dead. It's possible it could still be alive (it's described as an "apparent corpse"), but I'm not holding my breath. But again, there is no evidence to support the claims that it is bigger than any dreadnought, or that it would make an ideal weapon against the Reapers.