mmmm, interesting word - most of the noun definitions seem to share the physical properties of it being a 'thin bit of wood or pointy thing', don't they? But then there is one definition listed from times past that is distinctive, seeming to relate to 'tip' (as in 'out of your hand') perhaps:

slang. Obs.


A small gift of money; a tip.

1675 Crowne Country Wit ii. i, Give a spill to my watch, and my Grace shall drink your health in claret. {OED2}

And then there are the classes of meanings that definitely come from the verbal spill, as in something shed...


edit:
Just found this in another entry, whcih may give the derivation of the firelighter type of spill:

2. dial. In the sense ‘spoilt’, as spill-wood.

1847 Halliwell, Spilwood, refuse of wood, or wood spilt by the sawyers. South. 1852–83 in Hampshire and Sussex glossaries.