The event food Anniversary Ham states that it will increase your stamina by 25%. When you consume the food it visually shows you that it is active by visually increasing Guard by 25. Normally you have 100, see in this picture it was increased to 125 by the Ham;
With my testing, I consumed the food, then entered into combat with Halaster. I let him just hit my Hp first, then when he goes to do the first Annihilate, I hold up my Guard with it at 125/125. Then he hits me, I block it entirely and then he hits me with the Arcane blast which removes the remaining guard and breaks my shield. See here in the combat log:
If you add up those two numbers and multiply by 2 the number is equal to my maximum Hp value (because our guard is 50% of our max Hp). This should be higher if Anniversary Ham had any effect. 272554+223930 = 496484 x2 =
I hope this issue can be addressed. However if I am incorrect in my assumptions on how it works, please correct me.