At those dimensions and 1/4 inch glass I'd be tempted to do both a middle brace and eurobrace it. As far as the edges of the glass go I suspect it could be sanded to eliminate the sharp edges.
As far as a frame goes, I do believe that is what you are asking about, I'd probably epoxy up some molding then glue it onto the glass. People get hung up on thinking a thin piece of plastic is a brace, in most cases it's just something to protect the edges of the glass. An aquarium manufacturer I knew decades ago told me you design the tank so the glass will hold it, then you frame it to protect the edges... you don't need a one piece frame, it can be 4 or whatever because it doesn't provide strength. Just make sure the glass will support the water pressure.