I am wondering about the vessel used in hand washing, I see the ones with two handles online and in shul etc is it ok to use 'any' vessel to wash the hands or does it have to be one with two handles? For example, may I use a large cup or pitcher to wash hands or is there a particular purpose to the two handled vessel?
It is a practical matter. It is easier to wash without letting the unwashed hand touch the washed hand if the cup has two handles.
After the first hand is washed, it is clean and pure. The unwashed hand, however, is not. If the two hands touch after the first hand was washed, it is necessary to rewash the first one. We use a two-handled cup to make the process simpler, making it easier to avoid the hands touching each other.
You can use any cup to wash your hands, just be careful that the two hands don't come in contact with each other after the first one is washed.
Rabbi Eliezer Posner