There are several ways to accomplish a glow effect but this is my favorite. Normal all the channels so that the same source is in all 4. Put Defocus into  Channel 1B. Turn on a light source on 1A and rotate the joystick until it is visible. Go into your Keyer menu and turn 1A and 1B into a keyed pair.Turn up the Clip and Gain as SonyMan described until you start to see the higher luminance signals start to dial in wher you like them. Defocus channel 1B to soften the keyed edges. If you have the option that allows you to add trails you can get some cool tearing and smear effects on the keyed portion only. You have to play around in the combiner menu to find out how to see the Trails on 1A & B. You can also build a wacky glow in the Frame Store on a 3000  by feedin g the signal back into itself and blurring the framestore. Same technique. Key the framestoreover the video you want to blur. Send that same live video of the same source into the framestore. adjust the key signal, roll the video and watch a really 60's looking delayed video effect.

If it's a single twin put the same source in both channels. On the first channel blur out the image and ad color effects so bring up the contrast and color a bit to give a look you want. Now turn on the keyer so you are in VK mode Use the clip and gain controls to get the desired look. You could ad strobe for fun if you want. It's been a while since i've been on a Dveous, but I think this should work.