Like the Hammer, the Pincers remind us of the other trade that Jesus is commonly believed to have followed: that of a carpenter. But in fact, we know very little about the middle years of Jesus' life.
Traditionally, a son follows his father's trade. Matt. 13:55 says: "Is not this the carpenter's son? Is not his mother called Mary?" and Mark 6:3 says: "Is not this the carpenter, the son of Mary...". Yet none of the 46 parables in the Gospels refer to carpentry.
Whatever Jesus really did in those days is not nearly as important as what Jesus did in the last few years of his life. Through his sacrifice on the cross we can be saved from our sin.
When Jesus was removed from the cross, there is no reference in the Gospels to pincers being used to extract the nails that pierced his hands and feet, but that doesn't mean to say they were not used. Pincers were common tools 2,000 years ago for carpenters and blacksmiths, so there were probably some readily available.
When Pincers are seen adorning a cross, we are reminded of the nails that were used through the hands and feet of Jesus when He was crucified. More than that, we are reminded that the nails can be removed.
Each time we seek forgiveness from sin and abstain from sin, it is as though we are using pincers to lessen the suffering of Jesus.
How? See the Meaning of the Cross.