"**Brand**" will do.  

As in "He grabbed a brand from the fire and thrust into the face of the undead.."

In fact it is an interesting one.  Historically speaking "brand" means burning [Oxford Dictionaries : Brand ][1] from the Old English brand 'burning' related to German "Brand".

From here you get a Brand of wood from a fire, then to Branding Iron, then to the mark made by a Branding Iron - a Brand, from there to a mark in general - in particular a trade mark or a Brand.

I am glad you made me look that one up.

  [1]: http://www.oxforddictionaries.com/definition/english/brand