Crota had "luck", and it gave him "durability", until we killed his "soul". I know where "luck" comes from, I know what it really is. Luck is to be so important, to have roots so deeply entrenched into the foundation of the world, to have a legend so vast across time and space, that the universe itself conspires to preserve you until you fullfill your destiny. Causality becomes your most trustworthy shield. She fits the infinite pattern(just ask the FWC); thus she has luck.