I think the original Bug report is a little off in its description.
The each piece of armor has
Equip: Increases damage of healing done by magical spells and effects by up to (value).
With the added bonus of
(4)Set: Chance on melee attack to increase your damage and healing done by magical spells and effects by up to 95 for 10 sec.
The equip bonus seems to work
No armor: 48 damage
With full set 73
When the set bonus kicks in (Casting Crusader's wrath) there is no damage change at all.
Tested on level 60 Pally, 73 Holy Damage without Crusader's wrath bonus, and 73 with Crusader's wrath.
This change does not fix the original issue.
As a side note, Mangos Two accounts for this and has a change in damage (although slight) with the Crusader's wrath. buff.