@ladyjane - Your swan sounds beautiful and priceless. You must have been a very good employee that year. Venetian glass like any other glass is breakable.
Some of the heavier pieces such as the body of your swan are rather strong and less likely to break as opposed to say the neck or head. They can chip however, so take care not to drop them on a hard surface.
The Venetian wine glasses are very thin and extremely fragile but the Murano Beads are quite strong and durable just like a marble. But even glass marbles have been known to chip.