I also think flaming weapons doing extra damage through non-magical means is pretty dumb, especially since the game does have magic for that, but for game reasons I can suspend some disbelief and imagine an oil or chemical can burn really hot or something.
But I can't suspend disbelief enough to accept a metal weapon bursting into flame on a quick dip in fire, much less a candle. There should be some sensible limits to this nonsense.
