This is a way to create a magical-looking glow on an object, using Photoshop
Create a new layer. Using the polygon lasso tool, select the object you wish to make glow, in this case the sword. The selection doesn't have to be precise, because we're going to blur it later anyway.
With the new layer selected, create a mask of the selection. You do this by going to the layer menu and selecting Add Layer Mask: Reveal Selection. Now select the image portion of that layer in the layers window and fill the whole layer with pure white.
Duplicate the white layer and fill this new layer with a color of your choosing (although it should be a light shade). Blue is always good for a magical look.
Select the mask of the white layer and blur it by going to the Filter menu and choosing Blur: Gausian Blur. The size of the blur will depend on the resolution of your base image. In this case, I used a 20 pixel blur (the original image is much larger than you see here).
Now select the mask of the color layer and blur it the same way, but twice the distance. Once you've done that, make sure you still have the mask selected, go to the Image layer and choose Adjustments: Levels. In the levels window, pull the white point down until your blue layer looks like a fattened version of itself.
Now blur the mask of the color layer again, the same amount as you did before. Turn on both the color layer and the white layer, and put the white layer on top. At this point, your glowing object will look very much like a lightsaber. In fact, this same basic technique can be used to make lightsaber effects, but that's not what we're after here.
Simply set both layers to about 50-75%, and the blending style of the color layer to Color Dodge and the effect is complete.
Two of many possible variations on this effect can be made in the following ways. The first is done by selecting the masks of each glow layer and using the smudge tool in outward strokes to give a jagged or flame-like appearance. The second is done by adding Sparkles on top of the glow. (I went a little crazy with the sparkles)