Regal second-hand inoffensive

Well health potions are generally red which stems from the color of blood. There's a whole history of that in medicine pictures denoting it's, the medicine's, contribution to health. Mana, is derived from the ether which is just a fancy name for the clear sky; the upper regions of air beyond the clouds. When it's day time and you look up what color is the sky? Blue. So even though I did make this up on the spot it's a good enough answer that I'd buy it.