The phrase is perhaps slightly deceptive, because the phrase “cast of light” can be used without reference to a specific colour, in the sense of “the way light falls on things”, e.g. “an eerie cast of light”:

4 Nov 2009 ... The cast of light from it is softer and more directional and it gets rid of ... Return to the top of The British Journal of Photography ...
http://www.bjp-online.com/public/showPage.html?page=870636


However, the word “cast” clearly means a tinge or hue when it is linked with a colour-word, as in the following examples:


Eliminate the blue cast in shadows or from daylight - Friends of HDV
3 Sep 2008 ... A simple color correction tutorial to remove incorrect blue tint which may sometimes appear in your video.
http://www.friendsofhdv.com/.../remove-blue-color-daylight-s...


PSP's Automatic Color Balance adds a blue cast and PSP's Manual Color Correction tool adds a green cast in the dark areas and a pink cast in the bright area ...
http://thepluginsite.com/products/photowiz/colorwasher/compa...

* Daylight film - (Photography): Definition
The added bonus is that the inbuilt blue cast gives the sky an added boost of blue, ... carried a blue coating to match their balance to daylight film. ...
http://en.mimi.hu/photography/daylight_film.html


I certainly understood “cast” in the latter sense here, because it is linked with the word “blue”.


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Note added at 2 hrs (2009-11-26 13:37:05 GMT)
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I think of a "blue cast" as being a hint of blue - perhaps doing no more than subtly accentuating the blues that are already there - but obviously someone experienced it rather differently here:

These bulbs are billed as producing "daylight" equivalent light, and that might (technically) be true, but the intense (really!) blue cast of the light was really unbearable to my entire family.
www.amazon.com/Feit-Electric-ESL13T-Fluorescent-Incandescen...


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Note added at 2 hrs (2009-11-26 13:39:33 GMT)
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A subtle "blue cast", as often understood in the context of photography, is certainly not strong enough to make everything look blue; it may simply make the overall colour look colder (as I think one or two of the above links indicate).

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Note added at 21 hrs (2009-11-27 08:46:46 GMT)
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Yes, you could say "light with a blue cast" ...or "bluish cast".


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Note added at 21 hrs (2009-11-27 09:02:37 GMT)
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"recreating one of nature’s most challenging light sources" - the sun, I assumed. Correct me if I'm wrong. Not the moon, is it?
Daylight is said to have a blue cast: at least, I know that some daylight simulation bulbs are blue-tinted.
Taking the sentence as a whole, I understand the "cast" (hue, tinge) to be the all-important thing here. With the word "blue" right next to it, it's difficult to take "cast" in any other sense - though it has to be said, there is something ambiguous about the phrase "cast of light".

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Note added at 1 day4 hrs (2009-11-27 15:46:21 GMT)
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On your question whether "of" should be there at all:
Another possibility is that it should be "soft pale blue-cast light", i.e. a soft pale light with a blue cast.