I like the idea. However, I think it would make it even more awesome if it were restricted to the last guy alive in the battle server. So last guy on a team can be decapitated and can deliver them to enemies. Would make end round duels freaking epic.
If it were happening all the time during a battle or siege, it would just get excessive and cause a bad lack of taste i think. This idea for restricting it to last man standing is just an attempt to treat the bigger problem of taste brought on by introduction of gore. Its a happy middle between both extremes of the argument.