The Shaolin spade actually began as 2 seperate tools. A special spade that was used for digging graves, and a crescent blade for weeding. Both were much smaller than the current version. The crescent blade was very small, so that you could cut roots of the weeds and not damage the actual plants or bushes around the area. The Shaolin would commonly use these tools for farming, performing processions or burying the remains of animals that the would ecounter while they were travelling from one place or another.
When weapons became illegal to carry, the Shaolin found a loophole. They combined the 2 tools into one weapon and attached the spade on one end and the crescent blade on the other. There were no laws on the sharpenening of spades, so the Shaolin had an effective weapon to carry while still abiding by the laws of the country.
The spade is unique in the fact that it allows you to slice, stab or bludgeon your opponent. The spade end is fairly heavy and allows you to parry smaller headed weapons, such as spears, very easily. And, with a blade on either end, it also allows you to be offensive as well. The crescent can be used to trap or puncture, while the spade can be used to cut the limbs or your attacker. Add the range of a long staff, and you have one the most diverse and effective weapons in the Shaolin arsenal.