BeCu has some very interesting properties, though.
It makes one of the most incredible springs going, if properly alloyed and heat treated for that application.
When working it, it's a real bitch. It's very resistant to cutting. Very tough, gums up cutters, and is very "chewy" in consistency.
It has very favorable thermal properties. It's a better conductor of heat than pure copper, if I remember right.
Beryllium is also used in some industrial ceramics due to its ability to conduct heat well while also acting as an excellent electrical insulator. Very good for transmitter applications.
Beryllium is also a neutron reflector. A neutron bomb is really nothing more than a small A-bomb with a Beryllium shell. It generates immense quantities of free neutrons when it goes off, and those neutrons kill most if not all life in a larger area than the bomb's blast will.
CJ