Retribution: 355pts
S9 Torps,
FP18 Broadsides@45cm
S3 Dorsal Lances@60cm
Vanquisher: 300pts
S6 Torps
S4 Lances@45cm
FP6 Batteries@60cm.
The Retribution has 3-4x the firepower at 60cm . At 45cm the Retribution easily equals the Vanquisher's 4 lances, and has about FP8 left over. At less than 30cm, the Retribution owns the Vanquisher because it has a higher proportion of firepower in WBs that come into their own at short range. The Retribution is 55pts better than a Vanquisher, hands down, no contest.
It doesn't need Range 60, and it doesn't need to be cheaper than 355pts. It was flawed at FP12, undergunned and conflicted. But now it's fine, and it is not a bad thing that the Apocalypse outranges it and outguns it at that range - The Retribution still holds the advantage close up.
There's nothing wrong with the Retribution as fixed.