There is a concept in Judaism known as b'shinui - "with change". This concept is used when there is a need to do something prohibited. The basic idea is that by doing it with a change (in an inefficient manner), you're acknowledging that you realize you would normally not be permitted to do this, but need requires you.
Example:
One is not allowed to light a fire on the Sabbath, but if someone could get possibly get reasonably sick because of the cold, one would possibly be permitted to light a fire with his "off" hand - thereby acknowledging the general prohibition, but accepting that the laws allow for some leniency in certain cases. Note that if there was a chance of someone actually dying from cold, then lighting the fire on the Sabbath would be totally permitted, and in fact required.
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Not quite sure how this would translate into game terms, but maybe that character is protected by some divine power similar to how a threshold stops nasties. By using your "off" hand, you are therefore "acknowledging" that power, and this effectively "invites you under the threshold"?