Complex sentence: He was raised and educated by Bhishma as the half-brother of Dhritarashtra and Pandu, but since neither of his parents was of the blood royal, he was made counsellor to his brothers, the kings, rather than a king himself.
Split into simpler sentences: He was raised and educated by Bhishma as the half-brother of Dhritarashtra and Pandu. However, since neither of his parents was of the blood royal, he was made counsellor to his brothers, the kings, rather than a king himself.