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

Question

Let's say a character has the exalted feat Nimbus of Light (this is just an example) 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 kind of situations, where magical darkness interacts with supernatural light, and magical light interacts with supernatural darkness?

Answer 1

Light spells (Light, Daylight, …) and darkness spells (Darkness, Deeper Darkness, …) affect each other according to their level. If their effects overlap they either negate each other (if they are of same level) or the effect of the lower level spell is suppressed.

Since these spells do not mention light/darkness effects created by other (non-mundane) means or abilities we should assume that those are not capable of brightening or darkening areas of magical light/darkness unless they explicitly say so - like magic items or spell-like abilities that emulate spells generally do.

Some supernatural abilities that produce light/darkness effects also emulate spell effects, like e. g. the Darkness (su) ability of the Darkmantle (MM), which causes "darkness as the darkness spell". Others provide specific information on how their effects interfere with magical light/darkness, like the Sacred Radiance (su) feat (PH II, 89) which "temporarily negates areas of magical darkness created by spells of 3rd level or lower".

There is no rule indicating that supernatural light/darkness would generally interact with or trump over magical light/darkness.

So if an ability like Nimbus of Light does not give any further information or states otherwise, it is not capable of brightening an area of magical darkness.