I`m so confused about all the grades of weapons. Wish it said something about which grade is the best for each type of ship. It would avoid so much confusion with everyone.
There's some inconsistency in the game when it comes to Equipment grading.
Alot of Equipment such as Frameshift Drives or Shield Generators come in different Grades, i.e. E-Grade (lowest performance) to A-Grade (highest performance) within one class.
Weapons, however, only ever come in a fixed Grade per type. The Grading here is measured
across all different Weapons and comes with various caveats.
The Class 2 Gimbal Pulse Laser for example is graded "F", while the Class 2 Fixed Pulse Laser is graded "E".
- there is no such thing as Grade 2D through 2A Pulse Lasers, only the Gimbal, Fixed and Turret variants
- the 2E Class 2 Pulse Laser isn't automatically better than the 2F Gimbal Pulse Laser because in order to use the slightly increased DPS of the Fixed version one needs very good aim

There's other oddballs such as some Utilities like Chaff Launcher or Point Defense as well. Both are rated "Class 0 I" and there's no such thing as let's say a "Class 0 A" or even a higher Class Chaff Launcher or Point Defense.
Standard Cargo Racks are for example always E-Grade. As well, there's no "A-Grade Cargo Rack" with increased capacity or any other suspected benefits.
But once the two different grading Systems are understood (upgrades possible E to A-Grade, as found on many fixed and optional Internals) vs. fixed Grading (global, as found on Weapons and many Utilities), things get quite easy.