Initially, I looked into the Creation Kit for an answer:
In the screenshot we can see the
LeveledItem called LootImperialLuck. This is the ability Imperials have.
- Since all the Levels in the table are similar, the
LeveledItem upon activation will select one of those. This means that, in addition to the leveled loot already in a given container, those blessed with Imperial Luck will get 2-10 gold (each amount having a 100/9 % chance).
This seems to confirm the description given in the UESP entry.
Some additional information:
Calculate for each item in count option is ticked. As far as I know, this means that the chance of this ability (or the additional 2-10 gold pieces) being considered, is independent of the chances already calculated for the rest of the (default) loot (more on that here).
Chance None value (100) is determined by a
Global value. This refers to the
Global ImperialLuck, which is set to 100, when, according to the UESP, it is inactive (since "using the console command
set ImperialLuck to 100 disables the perk").
This use of values, which is counterintuitive, is more elaborately explained here:
Think of drop tables like throwing dice which can land on any number
from 1-100. If a container has a 30% chance of having an item:
1-30 = item is spawned
31-100 = item is not spawned
That blog post offers a very good readup on the four perks most directly involving finding more loot, among which is Imperial Luck (the others are Prowler's Profit, Golden Touch, and Treasure Hunter). Building on the information on the ability already given here, its description of Imperial Luck offers some new insights - disproving the common description in the process:
Imperial luck gives the player a varying number of dice rolls for each
type of container. The basic breakdown is as follows:
5 rolls - BOSS chests (except Falmer BOSS chests which give 1)
2 rolls - REGULAR chests 1 roll - All urns (except 'EMPTY' urns)
1 roll - Draugr corpses (the ones that don't come to life)
0 rolls - Dwarven chests (because screw you!) [and Strongboxes]
From what I can tell every roll has an equal
chance at landing on each of the 9 spots (meaning if one lands on '9
gold' it isn't eliminated). Over a large enough sample size you can
expect each roll to average an extra ~6 gold for you, so BOSS chests
will average ~30 gold and regular ones ~12.
I couldn't really find any information on what this power actually did other than most people citing that it adds 2-10 extra gold to a chest, which is not accurate. A pleasant surprise to me, the power is actually a lot more useful and profitable than I thought.
What's most interesting though, and what I found out about the latest (which is confirmed in that same linked post) is that every single player character starts out with Imperial Luck (Imperials have the exclusive racial ability that they are able to see it under their active effects) +. So comparing differences between an Imperial and a non-Imperial player character, to get an idea of the functioning of Imperial Luck in the vanilla game, is fruitless to begin with.
This bug is fixed by the Unofficial Patch (LE / SE).
+ Further down that thread:
"For clarity, in case anyone is wondering, the 'BUG' we're talking about is when you leave the Helgen cave at the start of the game a 'check' is done where certain racial powers/abilities are applied, one of which being the Imperial ability of 'Imperial Luck'. Bethesda being the top notch QA testers they are forgot to include a keyword that would make the game only apply the ImperialLuck if your character is flagged as an Imperial thus every character is given this power."