Function(s) of condenser in points-type ignition system?

It's used to prevent point arcing. Engines will run like garbage if at all with a bad or no condenser. Here's a quote:

The Primary Circuit
With the contact breaker points closed, a 12v current flowing from the car's battery induces an electro-magnetic charge in the primary coil (1). At the same time, a small capacitor, or 'condenser', placed in parallel to the circuit is also charged for an auxiliary purpose.
As the engine-driven distributor drive shaft rotates, a corner lobe of its campushes the contact breaker points open, breaking the primary circuit and preventing the primary coil from charging any further. The condenser acts as dampener at this point, preventing current from arcing (jumping) across the open gap in the breaker points, ensuring that the circuit is broken cleanly.