most take advantage of flashbulb heat. some (emperor, marauder, pillager, etc) use it with stealth. some don't have melee but are clearly meant to brawl (Ostsol)
additional options to those mentioned above
Black Knight NT-3B
Centurion D3
Daedalus 3D, 4A
Defiance 3C, 3S, 3T
Emperor 6L, 6M, 7L, 8L
Excalibur CS
Exhumer 3P
Gallowglas 3GLS
Grand Crusader II 03, 04
Grim Reaper PR30, PR31
Hammerhands 6D, 6E
Helios 6X
Koschei 6L (this one is especially funny with the sniper cannon)
Marauder 5L, 6L
Ostsol 6D, 8M
Pillager 5Z
Quickdraw 8P
Radier JL1, JL2
Raijin II A, C
Raven 3X
Seraph (the majority don't have a retractable blade)
Starslayer 3Dr
Thunder 2L, 3L
Thunderbolt 17S, 60-RLA
Tsunami P1D
Vanquisher 7R
Vindicator 5L
Warlord 2Dr