Belrustan had been a changed Elf, ever since the fight for the ships. ( had they not requested help from Olwe and been refused ). Before they had taken the ships they needed he had been a metalsmith, finding great reward in using heat and hammers to force metal into tools and weapons. In the taking of the ships he had found his passions inflamed’ there was something wondrous, almost a dance in the thrust, parry, turn and slash, of a battle. When he got into the rhythm of the fight, he cared not that his opponenets were his kin and he cared not for wounds for the sudden flash of pain merely inflamed his passion. When the battle was over and the ships had been taken he felt wondrous. The battle had made him feel better than any work at the forge was able to do.
Later, when Mandos spoke, and he had time to look back on his deeds, he felt shame at the passions raised in him by the fight. How could doing something so hideous make him feel so wondrous?. He stayed on one of the ships, sat and meditated on this; he had to find an answer; was it evil to feel that good? Was there a way to bring up those passions without doing evil?
In the Battle Under The Stars he found his answer. The Orcs could fight, and it troubled him not to kill them; yet it raised his passions to the same level. He would never kill another Elf, but instead dedicated his existence to the extermination of the hosts of Morgoth.