How do I animate a person taking out a sword from his back? I would like to have a human taking out his sword from his back. The sword is meant to be somehow tied to its back, but it needs to be pulled out.

I already did the arm movement, then imported the character into Unity, put the sword, and tried to see what happens. Unfortunately, the hand literally passes through the sword, so I figured out I had to do a particular animation for the guy pulling out his sword. Any suggestions? 

Should I have 2 separate objects in the same animation? Can i somehow put a bone into the sword or what would you guys suggest?

Edit: I need to mention 2 more things
1.I'm fairly new to Blender
2.I figured out I cannot attach the sword to his literal body, but I need to include it in the animation

Edit2: I read somewhere that by editing, I can put my post up again on the list, so here I am.. Sorry if I piss you guys off
Dude you need to use constraints to make your sword get attached with and follow your hand movement.I suggest you learn some concepts about how constraints work in blender.Apply constraints to your sword and set your hand as target to copy transformation.Then play around with the influence slider to get the desired result.You don't need a separate bone for your sword.See if it helps.