Weapon damage for crucible won't usually be the impact numerical value. For example, Doctrine of Passing is impact 2, but Crucible damage is 15/16 a crit. An Answering Chord is impact 28, but that isn't do 14x the damage of the Doctrine. When comparing rate of fire/impact between guns of the same type, it's more about putting them into 'tiers' than the actual numerical values. Like Malice will do less damage per shot (before barrel mods) than a Hung Jury, which does less damage than the Last Extremity. Damage generally won't scale at a rate that matches the difference between the impact stat. The Impact weapon stat is also relative to each weapon type. So comparing the numerical impact of a scout to an auto/pulse/hand cannon doesn't really work out either.