How does supernatural light interact with magical darkness, and vice versa?

Let’s say a character has the exalted feat Nimbus of Light which makes him shed light:

Your radiance sheds light as a common lamp: bright light to a radius of 5 feet and shadowy illumination to 10 feet. You can extinguish this radiance at will and reactivate it again as a free action.

What would happen if he enters the area of a Darkness spell?

Normal lights (torches, candles, lanterns, and so forth) are incapable of brightening the area, as are light spells of lower level. Higher level light spells are not affected by darkness.

Since the light is supernatural (all exalted feats are supernatural) it doesn’t qualify as "normal", it could qualify as a spell, but supernatural abilities don’t have "levels", and often, as in this case, they don’t emulate the effect of a spell like most spell-like abilities do.

So, what would be the proper way to resolve this situation?

  1. Should the DM assign a virtual level to the supernatural ability by comparing it to similar spells?
  2. Since supernatural abilities can’t be dispelled and are not subject to spell resistance would it be reasonable to assume supernatural light behaves like "normal" non-magical light, and it doesn’t shine inside magical darkness?
  3. Does any supernatural light trump over all kinds of magical darkness?