If we had to choose one tool as the most important, it would be the garden pruner. Small branches on perennial plants, shrubs, and trees can be cut or trimmed with a hand pruner.
A D-Handle/D-Grip garden spade is an indispensable and highly versatile tool for gardeners. It is without question the most essential tool for gardeners. If you don't have one, you can learn everything you need to know about them here. Every gardener needs one.
A simple shovel is one of the most essential gardening instruments. Shovels are ideal for excavating the majority of yard or garden materials. They are also helpful in breaking up and rotating compost and soil. Shovels have blades with a bowl shape and a convex edge.
Hand-forged, carbon and stainless steel are the most durable blade materials. Aluminium is lighter but weaker than steel. I would only construct instruments from this material. Carbon fibre is a lightweight, extremely durable material appropriate for handles but not blades.