Stats
There are 6 statistics that enhance the player character. Statistics have a value between 0 and 9.
The primary way of increasing stats is collecting Stat Up consumables, like 
Luck Up, that permanently increase a stat by one, or praying at corresponding Blessing altars.
Other ways to increase stats include:
The game doesn't track stats over max. This means that if you have a stat at 9 (max) and then gain and immediately lose a stat, your stat will drop to 8. This can happen if picking up and dropping 
Loki's Bargain when a stat is maxed.
Summary
| Stat | Effect |
|---|---|
Ability  |
Improves your abilities. Effect can vary depending on ability. Effect on items unknown. |
Damage  |
Increases weapon damage by ≈11.11% (100/9), rounded down. |
Luck  |
Better drops from enemies, chests and gambling shrines. |
Precision  |
Increases critical hit damage by ?. |
Range  |
Increases weapon range by ?. |
Speed  |
Increases movement speed by ?. |
Other upgradable variables
During playthrough, player can also upgrade two other variable - maximum HP and clip size. They are not tracked like offical statistics, but nonetheless increase incrementally similar to stats.
Maximum HP can be temporarily increased by 
Midgard Bracelet, and is permanently increased by 
Heart Container or by using 
Shield Converter while having armor. Maximum HP starting value depends on character and maxes out at 400.
Clip size acts as a bonus added to weapon's normal ammo capacity, and is kept between different weapons. This bonus starts at 0 and has no known upper limit. Clip size can only be increased by collecting 
Clip Up item.
