Couple of tips for you from an amateur like myself.
Glowing sources don't glow from the outside of the object. To create the illusion of a glow you need to put the lightest colors towards the inside of the weapon.
With that said, I get that the Darksaber has its white edges and I completely understand that drive. If you go that route though you'll need to sell the glow through light effects that bleed onto other parts of the model. This is relatively easy to achieve with an airbrush and some thinned down inks. Though that may not be something you have at hand and if that's the case, some glazing of the light color source on the closest parts of the model will help.
For the actual weapon and its colors, I can only say that pure black and pure white are rather visually boring. I prefer mixing my own blacks or at least adding to them which peoples eyes will pick up on even if they don't register it. I like to use a slightly yellow tinted white for a lot of my weapons though blue would also be suitable to your needs.
Also, while you're at this, consider watching some youtube videos on glowing weapons and OSL
effects. Tons of cool videos on lighting available there.
As for pitfalls, my biggest tip is to avoid gas station sushi. My second biggest tip is to just have fun. We all have to make mistakes to learn and grow. So if you make a mistake, just learn from it and try again.
Hope this helps and have fun.