All Vanguard ships can be defeated with missiles, PD, and strong reverse thrust ever since the update that increased the power usage to PD and increased splash damage with missiles.
Since PD drains power much faster, ships with poor supply routes will most likely have their PD idle. The Ragnarok and The Beast currently have an issue with powering its systems and will easily lose to missiles. Against the Ragnarok, all you need is your own PD to counter its missiles and destroy it with your own. The Beast has no missiles itself so you only need to target the reactors.
The increase to missile splash has made layered shields found on the Cerberus almost entirely useless. The PD on the Cerberus only covers the sides and has a risk of being destroyed by missile splash. The only dangerous thing about the Cerberus is that it becomes faster with more heads destroyed as it gets lighter.
The Drakon Sword and Twin Cruiser both require broadsides to fire most of their weapons and will never reach your ship. They will eventually fall to missile spam. The Drakon Sword especially since it lacks speed, shields, and good PD coverage.
The only ships that this strategy will have trouble with are Crescent Wrath and Archangel since they have a wide PD coverage (except the CW nose) and a decent supply route. With enough missile launchers (8+), a lucky missile may get through and strike a PD.
EDIT: So I just fought a Hammerhead and oddly enough, it has no forward facing PD. The head, fin, and tail has a side and rear facing PD on either side. When fighting my missile ship, it will turn and face its tail towards me in order to use its PD. While the Hammerhead has a lot of missiles, if your PD can counter them, you can overwhelm its meager PD and start picking off systems. If I remember correctly, the Hammerhead also lacks shields.
