However, you could use these options depending on the context:
General:
* A set of blades
* A collection of blades
* A bundle of blades
Specific to type:
* A sheaf of swords (for swords)
* A rack of knives (for knives)
* A quiver of arrows (for arrows)
Ultimately, the best collective noun will depend on the specific type of blades you're referring to and the desired effect.