Yamato Cannon - 14.4k avg. damage, +100% damage to shields, armor and hull.
Omega techs (from SOFE) in comparison:
Focused Divine Storm Discharger - 3.5k avg. damage, +50% shield and armor penetration, +200% hull damage.
Light of Pacification - 5.5k avg. damage, +25% shield and armor penetration, +100% armor and hull damage.
Tidebringer Warp Stellarcannon - 4.5k avg. damage, +25% shield and armor penetration, +50% hull damage, +100% shield damage.
From the stats alone, Yamato Cannon seems to be much more powerful than even omega tier titan weaponry, to the point that I wouldn't see any situation where I would use omega-tier weaponry over the Yamato Cannon. Phanon Tech is supposed to be inferior to Omega techs, and pretty much all of them are, but the Yamato Cannon sticks out as a clear outlier.