There is definitely something wrong with that model. I tried to fix a few problems with it and export but I couldn't because the model wouldn't show up in the exporter nodes list. Never had that happen before.
Okay first of all the blend files has a ton of knives in it. I'd start by removing everything but the one you want to export.
The model has double vertices so remove those.
Projectiles do not need armatures as far as I know and my projectile worked just fine without one.
When I parented the model properly (Mesh to detail32, detail32 to shape) it went haywire. I scaled up some 10 times and moved way off the screen. never had that happen before and it most certainly should not happen.
And here's your problem. The knife is UV mapped. UV mapping in Blockland is pure witchcraft and I've tried to do it forever but it just doesn't work. A wild guess based on a quick look at the pong projectile which is also UV mapped is that UV mapped objects in game do not receive shadows. They are shadeless and appear the very bright in the game. When mapped correctly that is. My attempts at UV mapping in Blockland have failed and resulted in the object being fully colored with one color from the texture. One time I was mapping a brown image with a black symbol on it, the object was bright brown in game. In this case the texture being mapped is transparent black. Since the texture is all one color, the knife in game is pure black all around.
Solution? Remake the model from scratch, do proper parenting and give it the proper materials and screw UV mapping. Here's something that might help:
http://forum.blockland.us/index.php?topic=157886.0I rest my case.