See, he's had practice at this. Of course, it could have turned out things were different here, but it seemed a fairly safe bet that the spell psychic field would have the same limitations as the trueberries.

"Oh, that wasn't the accident," he replies breezily. "No, that Dalek definitely shot him on purpose. No -- and it gets more complicated. There's a lot of energy associated with regeneration, as I'm sure you can imagine -- sort of a hodgepodge of energy forms, let's just call it regenerative energy, very useful stuff -- very volatile stuff. So, ah." And here's the part where he has to explain the hand, and that's really sort of embarrassing. "Well. Right after -- almost right after the last regeneration, he'd sort of gone and got his hand cut off." Swashbuckling and so forth, you know how it is. "Clumsy swordfighting, and you've probably got no idea where I'm coming from with this."

Handy sighs. "Not what I meant to say. But this hand was in a jar under the console of his ship -- don't ask how it got there, really, just don't."