The reason for his being crowned with heavenly glory is that he experienced suffering, suffering that consists of death. These words can best be read as a further explanation of crowned with glory and honour.
Christians suffering hardships may see the combination of the agony of death and exaltation as being incompatible, yet the author points to this suffering unto death as the actual reason for the Lord’s exaltation. Suffering is the path to glory. In almost mysterious brevity, the author wants to overcome any doubts of faith. It is the first time in the letter that the death of Jesus is mentioned (it was implicit in Hebrews 1:3). Death is the foremost hurdle for people to reach glory. Jesus clears this obstacle by eliminating the ruler of death (Hebrews 2:14). In this way he secures for his people the achievement of promised glory.1
9 But we see him who for a little while was made lower than the angels, namely Jesus, crowned with glory and honor because of the suffering of death, so that by the grace of God he might taste death for everyone.