Here is the look at the characteristics of the wise man as per various Upanishads.
The wise man is akamayamana. Every wish, craving, desire, all hope and fears have for him been destroyed; for all this presupposes an object to which it is related. Such an object however no longer exists for the wise man.
In truth, after that they have become conscious of this soul, wise men abstain from desire for children and possessions and the world, and wander about as beggars. For desire for children is desire for possessions and desire for possessions is desire for the world; for all together are vain desire. (Brihadaranyaka Upanishad. 3.5.)
This is the men of old time knew, when they ceased to long for descendants and said, what need have we of descendants, we whose soul this universe is. (Brihadaranyaka Upanishad. 4. 4. 22)
Gaudapada sums this up briefly and strikingly in the words: — "What can he desire who has all?" The wise man therefore no longer experiences fear. (Mandukya Karika 1. 9.)
He who knows this bliss of Brahman is not afraid either now or at any time (Taittiriya Upanishad. 2.4.).
He is no longer vexed by anything (Katha Upanishad. 4. 5. 12).
For wherefore should he fear? since fear assuredly is of a second. (Brihadaranyaka Upanishad. 1. 4. 2.)
The knowledge of the atman transcends individuality, and therefore the possibility of pain. He who knows the atman overcomes sorrow. (Chandogya Upanishad. 7. 1. 3.)
He who is in the body is possessed by desire and pain, for because he is in the body no safeguard is possible against desire and pain. He however who is free from the body is not affected by desire and pain. (Chandogya Upanishad. 8. 12. 1.)
He therefore who has crossed this bridge is like a blind man who gains his sight, like a wounded man who is healed, like a sick man who becomes whole. (Chandogya Upanishad. 8. 4. 2.)
And his works become nothingness. (Mundaka Upanishad. 2. 2. 8.) All works, the good as well as the evil, become of no effect for him who has attained knowledge, as is often affirmed. For the individuality which gave rise to them is for the wise only a part of that great universal illusion which he has succeeded in penetrating.
For the same reason future works no longer cling to him, as the water does not cling to the leaf of the lotus flower. For him to do evil is entirely excluded by his freedom from all desire. "Therefore he who knows this is tranquil, subdued, resigned, patient and self-controlled. He sees the Self only in himself, he regards everything as the Self. Evil does not overcome him, he overcomes all evil . . . free from evil, free from suffering, and free from doubt, he becomes a Brahman, he whose universe Brahman is. (Brihadaranyaka Upanishad. 4. 4. 23)
"Whereby does this Brahman live? By living as chance may determine." (Brihadaranyaka Upanishad. 3. 5.)
His future condition, as far as the bodily state is concerned, which he has cast off like the skin of a snake, is entirely without importance: No matter whether a man wish for himself A hundred years, pursuing his work; Remain then, as thus thou art, not otherwise, The stain of work clings not to thee. (Isa Upanishad. 2.)
"He who has reached this state in truth feels no doubt"; (Chandogya Upanishad. 3. 14. 4.)" for him all doubts are solved"; (Mundaka Upanishad 2.2.6) "free from doubt he becomes a Brahman." (Brihadaranyaka Upanishad. 4. 4. 23). Because the knowledge of the atman does not depend on reflection (tarka) (Katha Upanishad 2.9), but on immediate intuition (anubhava), therefore he can no longer be shaken by any doubt. The illusion, when once it has been penetrated, can no longer delude. The question of the possibility of a relapse is not and cannot be raised.
Source - Emancipation By Paul Deussen The Glory of Self-knowledge published in “The Mountain Path” December 1997 Issue. Page 128 to 130