Question

how come when the battery was short circuited with spanner holding it with bare hands prof. has not experienced any shock

Answer 1

The battery was shortcircuited, while the good professor did not suffer a shock, he may end up with burned hand depending on the capacity of the battery lol.

Answer 2

this must be because of the better alternate conduction offered by the circuitry of the short circuited battery

Answer 3

Yes, with the spanner wrench, assuming it is made of a good conducting metal, across the battery terminals they are essentially at the same potential, without sufficient difference in potential the professor is relatively safe. Now if the battery itself is connected to other circuitry with power sources it might be another story. But the important point, is to consider safety. The professor is not using good judgement and is setting a poor example for his students.