The [Acc] modifier stands for "accuracy." The more accurate a weapon is, the more favorable it is because it hits its target more often. Damage modifiers are nice, but they don't do you much good if you don't hit the target.
Accuracy overcomes defense (fast targets, skills, or just passive missing). Missing is random, but can mean big losses of damage if it's on a big attack. Not only does it mitigate damage loss, but excess accuracy above the maximum chance to hit is redirected into crith and critd.
On a side note, this is the same episode where they actually start going more in-depth w/what we're seeing in Season 6, so you may want to watch it from start to finish. It's a bit impressive that they introduced the Starbases w/in the timeline they predicted.