Where is the sword from, kinda hard to even considering helping without some of the basic information.
Paizo Employee James Jacobs Creative Director Oct 31, 2013, 02:33 pm | Flag | List
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James JacobsRadiance is intentionally meant to be a "free upgrade weapon along a specific path." It's not meant to be one a player upgrades on their own with cash; a player seeking that route needs to use any of the other numerous weapons in the game.
OR go the legendary item route with mythic tiers, which does indeed bolster the weapon beyond what it can already do and will eventually turn it into a major artifact.
And yes, it is quite powerful. As are lots of mythic options. Don't worry! The bad guys get powerful toys too! :-D
A quick search turned that up, so looks like 'No' would be the answer, unless the power/ability is one available through the legendary weapon options in mythic advancement.