The other problem with research is that the Shade usually performs (in public, at least) at less than peak performance. Prometheus might be under the impression that the Shade isn't capable of using his powers in a fatal manner. Or (worse yet) that Shade can't use his powers without his cane.
That's a beautiful scenario, isn't it? A misinformed Prometheus attempts to disarm the Shade by slicing away the hand that holds the cane. Thinking that the Shade has collapsed from shock after having his hand cut off, he goes to investigate the cane, thinking to see if he can get it to work for himself. But Shade was just playing possum, and after a short interval of darkness, all that's left of Prometheus is a red stain and that helmet of his.