Subtle Low Level Light - Rusty Weathering Steel

The glass part of my light is broken - is it possible to buy the glass separately either from you or the manufacturer? I'd like to avoid buying a whole new light - Thanks
Yes, spare glass is available to purchase

Are these securely sealed against water ingress? Can I see diagram showing how they are put together? Can I order one in order to inspect and return if it doesn't look up to the job?
These fixtures are IP54. The second digit indicates that this will withstand splashes of water from any direction. In practical terms you should not get the pressure washer out to wash these fixtures (not that you would need to). The cable entry is on the base. It has a simple grommet; to improve water resistance you could ensure a good seal where the cable or flex comes through the grommet (silicon would be sufficient). These lights are popular and we have not had issues with water ingress. This is a two part construction - you will not need instructions but they are supplied. NOTE: If you are considering using this in an areas that has standing water, ensure you improve drainage before installing this fixture, or use a fixture that has a rating of IP66 or higher. We offer a returns policy so you can 14 days to change your mind, but you won’t need it.

Can this fixture be installed on a north american circuit 110 volts/ 15 amps ?
The issue is availability of lamps. In the US we understand that only E17 and E26 lamps are available. This fixture uses an E14 lamp. These are commonly available in Europe but not widespread in the US or Canada.