from The Century Dictionary.
- noun A sheet-metal guard used to protect workmen at a furnace or firemen at a fire from the heat.
Sorry, no etymologies found.
Some woods, you know, burn well when green and some woods must be made dry before we can use them for fuel; but the wood we want for the fire-shield is the sort that will not burn readily; the good-burning woods we save to use in our fire.
"It's a variation of the fire-shield I raised; it's magical energy manifesting itself in a physical fashion.