Enormous Crest-built transports assumed to be defenseless, which is exactly what makes the Homecoming Queen deadly.
Crest behemoths are the largest ships in the sky and are not known for their defenses - an assumption so universal that nobody in Earth orbit ever attempted to shoot at the Homecoming Queen during the fighting, and York notes it would take an enormous amount of energy to knock one down anyway.
That reputation is the disguise. The Homecoming Queen is heavily armed, a secret York has worked hard to keep, and carries a full complement of enhancement zone guns and beams that Porthus had installed. During the orbital shooting it destroyed The Orc Yacht and then appeared to flee the conflict with the other transports, and by the epilogue it is very likely the strongest warship above Earth - precisely because nobody counts a behemoth as a warship at all.
Immense civilian-pattern transports, the largest vessels in orbit, built by Crest and presumed lightly defended.
The ship class whose harmless reputation hides the resistance's most powerful weapon.