Shields are designed to protect.  As the crab and lobster need a hard outer-shell to deter strong jawed fish, and the snail retreats into its shell, so human beings have developed all kinds of protective shields for physical protection.  Today's police riot shields imitate the Roman military 'scutum' (shield) although using different materials. The scutum was about 120cm high, made from curving thin layers of wood to form a semi-cylindrical shape 5-6mm thick (an early kind of laminated ply). The wood was covered with leather and edged with a bronze strip.

This 'cut and thrust' is not about sharp business practice or 'positive driving'.  It is about an essential defence against the Evil One.  Most readers will never have held a sword, and certainly not used it as a weapon.  The Roman infantry gladius sword was about 60cm long, made of some sort of steel-like alloy.  Although the mounted officers would have a longer spatha sword (about 1 metre) this would be too unwieldy for the foot soldier.  The gladius was broad-bladed and double-edged for cutting and slashing, with a well-formed point for thrusting.

When you see, ..."with this in mind" we should ask, "what is the 'this'"?  Paul has just explained that the opposition faced by Christians is nothing personal to them.  But it is personal between the devil and the Lord.

Networking is not a new business strategy.  Tychicus was one of Paul's personal assistants, who was trusted to share Paul's news and encouragement around the churches (Colossians 4:7-9). This was classical networking.  Everybody felt that they were known and could get to know others better.  But this was not just a series of social encounters: the key communication was about Jesus.