The affix tasi comes after that Instrumental -3rd case which does not denote an agent and is governed by a verb having the sense of 'to excel', 'not to give away' and 'to blame'.,
Thus वृत्तेनातिगृह्यते or वृत्ततोऽतिगृह्यते, चारित्रेण or चारित्रतोऽतिगृह्यते ॥ This means when a person of good conduct surpasses others through his conduct, he is said \to have excelled through his conduct and character\. So also वृत्तेन or वृत्ततो न व्यथते; similarly चरित्रेन or चरित्रतो &c, the sense being he does not succumb or is not moved owing to his strength of conduct or character. Similarly वृत्तेन or वृत्ततः क्षिप्तः, चरित्रेण or चरित्रतः क्षिप्तः \blamed owing to his bad conduct\.
Why do we say \when not denoting an agent\? Observe देवदत्तेन क्षिप्तः \blamed by Devadatta\.,