Answer:
Often found in doctor's offices and pirate flags
What has one head, one foot, and four legs?
I am not alive, though I never die, to no one I've ever told a lie, today I can be god's warrior, and serve him with no horror, but tomorrow I might be devil's knight, for I am what ends the light.
What must you give before you can keep it?
What can you hold in your left hand but not in your right hand?
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.