Student dissatisfied with exam grade: what to watch out for?

A student who has trained hard for my exam got a just-passing grade. They are dissatisfied with it, and have mailed me to ask to have a look at my corrections. Naturally, I agreed to this. In the mail, they are already calling into question my corrections and the exam content. Is there anything in particular I can do at this point to minimize the chances of a dragged-out discussion or procedure with the exam committee?

Crucial info:

1. The course I gave was extracurricular, and planned to be pass/fail based on participation. I only added the exam after this student asked for it, because they needed a grade for some administrative reason. The exam was taken by a very small number of other students (inadequate comparison material).
2. At that point, I asked the student if they aimed for a particular grade, and the answer was 'no'.
3. The student got all knowledge-based questions right, and flunked almost all applied knowledge questions.
4. As the course was extracurricular and covered an advanced topic, I made sure to cover the basics, but on top of that I covered a lot of content quickly, allowing advanced students to learn additional things if they wanted to.
5. I suspect this student simply missed the bulk of that information, partly due to a language barrier.
6. During correction, I already scrapped one question from the exam that no-one got right and that strongly seemed like I had mentioned it too passingly during the course.
7. After calculating the grade based on a linear transformation of the point score, I felt that the best grade (which was moderate) did not give credit to that person's understanding; besides, the student discussed here would have received a fail grade. I added two point-increments to the final grade, fixing both of these issues.

By asking for an exam, the student asked you for a fair, honest, informed evaluation of their mastery of the course material.

If you believe that the exam grade fairly and accurately reflects the student’s mastery of the course material, say that, and explain why. Be respectful and honest. Stick to your guns.

In particular, you should have some record of your announcements of both the contents of the exam (“How was I supposed to know this?”) and your expectations for certain grades (“Why did I get this grade?”)—the course syllabus, or a handout, or email to the students. You should have sources/proofs for the correct answer for each question (“Why is this wrong?”), rubrics for awarding partial credit for partially correct or suboptimal answers (“Why did I get so few points?”), and well-reasoned rules for converting raw exam scores to reported grades.

If you do not believe that the exam grade fairly and accurately reflects the student’s mastery of the material, then you need to reevaluate the exam for all students. You’ve already done this by throwing out one question and curving the scores.