Er guys...hello...reality check...Havent you forgotten a very simple law from that Newton bloke. You know, the one about every action having an equal and oppersite reaction?
Think on this...You fire your spike into a bot that is sitting against the arena side wall..with me so far?..good! and because this bot is armoured like a proverbial brick built s**t house your spike doesnt penatrate but just comes to a standstill...see were Im going yet?? Let us say you go for a pneumatic spike with reasonable thrust...12Kg robot goes flying backwards having recieved nearly all the energy intended for its victim!!..Ok, extreme example but it holds for all situations. You only have 12Kg to hold this weapon on the arena floor. The moment you impart more than this into your opponent you will recieve an equal amount in return!
Just a passing thought on reading this thread

Geoff.