Obsidian is basically glass with some impurities that make it absorb light. Like glass, it is very brittle, and makes terrible, very heavy armor. It can take a razor sharp edge, so is useful for weapons, if you don't mind the edge on your weapon snapping off anytime you hit anything harder than flesh.
What I think you want, rather than actual obsidian, is a metallic glass. This is a substance made of a number of different metals melted together, and then cooled so rapidly that the metal has no time to form a crystalline structure. This results in a very hard, durable substance that shares properties of both metal and glass. Vitreloy has a tensile strength double that of titanium, and there are tungsten alloys that have hardness double that of carbon steel. When heated, many metallic glasses will become extremely malleable, and can be easily molded like hot plastic.
The field of metallic glass is still very new, and experiments finding new alloys are being done every day. It's not unrealistic to think that one might be found that has a glassy black look with a hint of gold. The color of alloys sometimes has nothing to with their components. For instance gold-aluminum alloy in the right proportions will be a vibrant purple. Gold infused glass is called cranberry glass for its bright red color, and titanium infused glass is yellow.