When the laborers of Nehemiah's day rebuilt the wall of Jerusalem, they worked with one hand and held a weapon in the other (Neh.4:17).
Since then, the sword and the trowel have become metaphors for simultaneously building something up while staying vigilant against enemies.
The problem in our day is we get so preoccupied with bogeymen we don't have much time and energy left for the work of God's kingdom.
Nehemiah teaches us wise living figures out how to stay aware of dangers while keeping at the work God calls us to fulfill.