Okay, this is cool.

[novapsyche]

flaw, c.1325, "snowflake, spark of fire," from O.N. flaga "stone slab, flake" (see flagstone); sense of "defect, fault" first recorded 1586, first of character, later (1604) of material things; probably via notion of a "fragment" broken off.

One word whose root is a pair of diametrical opposites.