Forged and Ready for Battle - Mark

Exodus 13:17
It so happened that after Pharaoh released the people, God didn't lead them by the road through the land of the Philistines, which was the shortest route, for God thought, "If the people encounter war, they'll change their minds and go back to Egypt."

The path of least resistance produces weak people. Testing and forging increases our faith and develops a habit of total dependency on God.

Wikipedia:
Swords can be shaped by a variety of metalworking techniques. Forging uses heat to bring the material to a malleable state. The material is then hammered to shape, typically using hammer and anvil.

The final step of forming, and one that affects both the finishing and the heat treatment is 'normalizing'. The blade would be carefully and evenly heated and then cooled slowly. The point of normalizing is to remove the stresses which may have built up within the body of the blade while it was being forged. During the forging process the blade might be heated and cooled differentially creating stress, some parts might be hammered more than others, some areas hammered enough to "work harden". If these stresses are left in the blade they could affect the finishing and when it came time to heat treat the blade, the hardening and tempering might not be as even. Potentially enough stress could be added that the blade would be weak in spots, weak enough that it could fail under enough strain.

Trials remove the small stress fractures, producing strong Christians, ready for Spiritual Battle.