Wrath & Glory Blessed Trait rules

Hello, I have an uncertainty about the "Blessed" weapon trait. The rules for it are stated as "Blessed weapons gain +ED equal to their rating when you use them to attack a target with the [PSYKER]() or [DAEMON]() Keywords."

What determines a weapon's rating? At first I thought it was the rarity, but the Blessed Blade at rarity 3 shares the same Blessed rating as the Condemnor Boltgun at rarity 4.

Any help would be greatly appreciated.