Generally speaking, you would want your business card to be legible and downright loud. A big part of the reason why that is the case has to do with the fact that if your business card uses incredibly muted colors, chances are that no one would ever get the chance to figure out what it is that you are actually talking about and this is not going to be all that ideal for you if you think about it. The thing to note about business cards and the like is that sometimes you would want the information contained therein to be rather clandestine in some way, shape or form at any given point in time.
While this might go against the overarching ethos of the use of Metal Business Kards in various industries around the world, it should still be noted that certain industries and professions will want to make themselves a bit more exclusive if you think about it. This means that you might want to try creating business cards that cater to this crowd, and using glow in the dark ink can be a great step in the right direction for you.
The main benefit of using a business card that has glow in the dark ink on it would be that first people would not see anything on them and this might make them assume that you have simply handed them a blank card that would offer no real value to them whatsoever. However, if you tell them to see the card under cover of darkness, they would be surprised to see what they see and this will make them extremely intrigued as well.