1)
What is the meaning of "Samuch Libo"?
1.
Rashi: He relies on and trusts in Hashem. Radak - therefore, he does not fear people.
2.
Malbim: He does not fear lest his enemies do evil to him, for his heart relies on his virtue.
2)
What is the meaning of "Ad Asher Yir'eh v'Tzarav"?
1.
Radak: He sees the evil that he wants to see in them. This is like "uv'Oyvai Ra'asah Eini" (54:9) - my eye saw in them what I wanted.
2.
Malbim: Not only does he not fear his enemies - he even sees vengeance against his afflicters.