In Vanquish, each weapon has a unique melee attack. So here’s a guide for a few of them:
Assault Rifle: Flurry of jabs w/Finisher punch
Heavy Rifle: Backflip kick
Shotgun: Slap
Rocket Launcher: Uppercut
Disk Launcher: Buzzsaw
And no tip guide is complete without an Achievement tip! This’ll be a special tip, because with this you can unlock two achievements at once. The two achievements are “Romanov this!” and “Brutality Bonus”. The get Brutality bonus, shoot off a Romanov’s limbs (preferably w/Disk Launcher) and beat the life out of it with melee attacks. If you destroy it in this manner, you’ll also get the “Romanov this!” achievement for defeating a Romanov with melee attacks.