Albert Barnes on Hebrews 9:26

For then must he often have suffered. That is, if his blood had no more efficacy than that which the Jewish high priest offered, and which was so often repeated, it would have been necessary that Christ should have often died.

But now once. Once for all; once in the sense that it is not to be repeated again--απαξ.

In the end of the world. In the last dispensation or economy; that under which the affairs of the world will be wound up. See the phrase fully explained Heb 1:2; Acts 2:17; 1Cor 10:11, Isa 2:2.

Hath he appeared. He has been manifested in human form.

To put away sin.

(1.) To remove the punishment due to sin, or to provide a way of pardon; and

(2.) to remove the stain of sin from the soul. Heb 9:2.

By the sacrifice of himself. Heb 1:3; Heb 2:14; Heb 7:27.