The ice guardian shield gives a 5% bonus to your defense stats. What this means: At full troops, you receive the full 5% bonus to your stats from this equipment. At half troops, you receive half of the 5% bonus. Ie: if you have 1mil bta that is equivalent to 50 mil raw stats. So you will see 2.5mil bonus on your equipment page. However, as your troops lower, so does the stats of the shield. So when you have 500k bta or 25mil raw @ 50% troops, the shield will only give out 1.25mil raw bonus