How is a "Chacham Yarei v'Sar me'Ra"?
Tanchuma (Lech Lecha 15): We read this Chacham v'Sar me'Ra Yarei; this refers to Avraham.
Rashi: He fears punishment, and veers from evil.
R. Yonah: A Chacham, even though he veers from evil with all his ability and desire, he fears lest he err in his deeds and fall short of his obligation 1 . The end of the verse supports this.
Malbim: Chachmah needs Musar. In all Midos there are two ways. One way is Chachmah, and the other is folly. The Yetzer ha'Ra leans towards evil. The images planted in his heart from birth lean towards desire and physical pleasure - the opposite of the way of Chachmah. When the Yetzer ha'Ra entices him to lean away from the ways of Chachmah, it is easy to heed it. He needs a matter to chastise the powers of his Nefesh, lest they leave the boundaries of Chachmah. This Musar is Yir'as Hashem. He knows that a great King stands over him and sees his deeds. He is ashamed and afraid to do something against His will. Therefore, "Reishis Chachmah Yir'as Hashem" (Tehilim 111:10); it is a requisite for Chachmah and the gate to it. A Chacham, because he fears Hashem, via this he veers from evil. He does not lean away from Chachmah's counsel, for Musar chastises the powers of his Nefesh not to leave the boundaries.
Sha'arei Teshuvah (4:16): We explain Chacham Sar me'Ra v'Yarei.
How does a Kesil "Mis'aber u'Vote'ach"?
Rashi #1: He invigorates himself to transgress strongly, and he slips and falls to the ground. This is like "uv'Eretz Shalom Atah Vote'ach" (Yirmeyah 12:5). Yonason translates there 'At Misbetach v'Nafel.'
Rashi #2: Vote'ach is an expression of trust. In his palace, he trusts to say 'evil will not come to me.'
R. Yonah: A Kesil, even though he does not veer from evil, rather, he approaches evil, he trusts that sin will not occur to him, and that his path is clear. The verse details his sins - quarrel and anger. From them come hatred and damage from people. Even so, he does not fear, and trusts that he will not stumble. Sha'arei Teshuvah (4:16) - this is the opposite of a Chacham's Midah.
Orchos Tzadikim (Sha'ar ha'Simchah DH ha'Bitachon ha'Rishon): This refers to one who puts himself in danger, and says 'I trust in Hashem.'
Malbim: A Kesil crosses the boundaries [of Chachmah's counsel] and trusts [that he will not be harmed]. This Bitachon is the opposite of fear! He does not fear Hashem and His grandeur.