NI$HANT:
Upgrade the wrist thingy to a GLCD. You can get a 128 x 160
Don't you think its too big for a wrist even a GLCD 128x64 is Big also the size of a Wrist mountable LCD would be > Wrist watch as much big as it doesnot become a overhead on your wrist.
I think the LCD the one i attached is the most appropriate, rest is your choice
The one you link is 128 x 128 plus the added size of the breakout which actually makes it larger than the bare 128 x 160 that I am talking about. So what exactly is the difference? I got the point that he had it on his forearm since having even a 16x2 on his wrist would be a bit wonky and a 128 x 160 on the forearm is not too big at all.
What would I gain from using RFID
I agree, it actually adds zero value to the project since the goal is to transmit data from the gun to the screen. If you are transmitting data, either hard wired or wireless, you can bypass this added expense. If you are going to stick to wired for now, just add a second connection so the guns plug into different 'ports'. Adjust your code appropriately and your problem is solved although it is still obviously a bit clunky. Also, RFID buttons may be cheap but the cheapest reader I have seen is $30. That is not cheap.
I really like the idea of adding the display to the gun itself. I have a 4D systems 1.4" and I have thought many times about adding it to one of my modded nerf guns to make it look cool. I have many but the Vortex Praxis is virtually made for this kind of mod. I already added an LED in the bottom of the magazines that light up when you insert the magazines into the gun.
If you are thinking of going this route then I would suggest using this same display. It can be used completely independent of a uController. You just need regulated 5V and you are in business. They aren't as cheap as other displays but since it drastically reduces the peripheral components and the project is really simple, the cost of this display would be well worth it. Sparkfun sells them but they are currently out of stock.