I made the decision to put the spinning blade in the middle of the robot with 2 wedges leading up to it. I did this because of the problems other vertical spinning robots have had with side impacts on their exposed blades. When a spinning blade is hit from the side significant damage is done not only to the blade but to the entire subsystem.
The other major factor is the gyroscopic effect. When a blade spins it wants to keep the mass of the robot going in the same direction. This is amplified by the fact that the blade is off centered. By placing my blade in the center the gyroscopic effect was minimal.
The flaw in my design came from the skirts which lead into my wedges. I used light polycarbonate instead of spring steel. In the first match these skirts got damaged and I didn't have replacements. This diminished my ability to get under competitors rendering my blade useless.
If I were to do this again I would either replace the skirts with spring steel or remove a wedge all together and have an exposed blade. I feel that the risk of having a fatal hit on my blade would be worth being able to use my weapon.
I would change my batteries from SLA to NiCad to gain a few extra lbs and increase the size of my weapon motor. I also used .5" aluminum for the sizes and .25" for the base. I realized this is way overkill for this size machine and I could loose some more weight off the system by optimizing.
I am still happy with the result of this project as it challenged me in lots of ways. The other thing is I pride myself in is building robots unlike others. For better or worse my machine was different and I enjoy knowing that my idea was new into the world.