The main benefits of Shears are the increased yield and decreased harvesting time when gathering resources.
Using Shears on Tall Grass will net 2 Cut Grass and require only one use, in place of the 1 Cut Grass received from three uses of a Machete. Similarly, Shears can be used on Hedges to harvest 2 Clippings instead of just 1 when using a Razor.
Assuming the player uses the Shears only to sell collected resources, one set of Shears will earn the player 40 Oincs, or 2 Oincs per use. Hanging Vines can be cut for 1 Rope, which can be sold to Worker Pigs for 2 Oincs each, Hedges can be cut for 2 Clippings to be sold to the Shopkeepers for 1 Oinc each, and Tall Grass can be cut for 2 Cut Grass and sold to Farmers for 1 Oinc each.