1). When though is used with a verb in the subjunctive mood (expressing doubt, a condition contrary-to-fact, a wish, a concession) is followed by yet and not by but;
Though he might not have recognized me, yet it is rude of him.
Though she disallowed me, yet I will go to her.
Though he is poor, yet he is respected.
2). When though is used with a verb in indicative mood (expressing a fact or making a statement) a comma is used in place of yet.
Though he is my relation, I shall not spare him.
Though she is known to me, I shall not favour her.