Is a switches voltage and current rating a hard limit?
The answer to this is closely related to the answer to an old question about connectors.

As in the connector question, the main thing you need to remember is that the current through the switch and the voltage between the switch and ground don't tell you the power consumed by the switch. Typically they tell you the power consumed by the load.

But with switches the failure mechanisms are slightly different than in connectors. While the current rating is typically related to \$I^2R\$ heating at the contact, the over-voltage failure meachanism is typically reduced durability due to arcing across the contacts during making and breaking, rather than breakdown in the material between the terminals.