Here’s the picture:
The legendary affix is a separate multiplier. The normal skill affix is additive with other normal affixes of the same type, meaning it’s added to them to form another multiplier.
Quiver 1:
damage multiplier = 6.34 * (1 + 0.15 + other additive bonuses)
Quiver 2:
damage multiplier = 6.61
If you don’t have any normal HA affixes on other pieces, quiver 1 has total multiplier of 6.34 * 1.15 = 7.291. However if your pants and belt have 15% HA damage as well, quiver 1 is 6.34 * 1.45 = 9.193 and quiver 2 is 6.61 * 1.3 = 8.593. Quiver 1 is better.
Multiplicative and additive modifiers can get confusing a bit but this should help: