Mat 10:13 And if the house is worthy, let your peace come upon it: but if it is not worthy, let your peace return to you.

First, notice that you start by embracing the house and it family members. Only afterwards do you detemine whether or not the house is worthy. This is why I said that Christ's earlier statement about seeking out the worthy people was NOT as statement about staying at their house but rather an analysis of the city or village.

Here, the term for "worthy" is the same, axios, which means weight, specifically as a counterbalance to something of value. (Matthew as a tax collector would have been very familiar with this idea).

"Peace" is the Greek eirene. Eirene was the Greek goddess of peace. The term means "national tranquility," "harmony between individuals," and the general idea of safety, security, and prosperity. It is the opposite of the state of war.

"Come" is the Greek erchomai, which means to come to a place, but metaphorically "to come into being."

"Return" is epistrepho, which means "to turn about" or "to turn around," but also means "cause to return" and "to turn one's mind towards" something.

The sense here is that we want to create a sense of peace and trust between ourselves and worthy people, that is, those who see the value in what we offer. However, if people do not see the value in what we offer, we can still be at peace with ourselves. We need not be troubled by their rejection of what we believe.