Final answer:
The sentence in question is grammatically correct with proper subject-verb agreement and no misuse of reflexive pronouns. There is no need for additional punctuation or adjustments.
Step-by-step explanation:
The sentence "She claims she did it in self-defense" does not require any corrections in terms of grammar. It is clear and concise, with the subject "She" clearly identified. The directly quoted statement is a claim made by the subject, and as such it does not require additional punctuation or adjustments in its form. Furthermore, the sentence follows proper subject-verb agreement and does not misuse reflexive pronouns. In this case, the pronoun "she" is appropriately used, and the reflexive pronoun "herself" is not required nor would it be grammatically correct to include it here. Also, because there's a single independent clause with no introductory phrases such as an infinitive phrase that would require a comma before the subject, the sentence stands correct as written.