I dropped it, so can't buy it back and I tryed buying a new one but evey time I try to equip it would remove my current main saber?

Before I start I know I'm a tool lol , I have chosen my class as a sith assassin Apon receiving my second offhand sabre I buy clicking away discarded it, I Know right!?! My question it's how can I get another offhand saber? We're? And How To equip it?