Corrupt Charge is used because Heavy Attacks use the same animations as normal attacks, with no wind-up time, meaning they're free bonus damage, so you should always be using heavy attacks.
[Life Strike] is used because even with the Heavy Attack quirk this weapon has, it just has kind of terrible stats, meaning that the main use is utility, like for restoring health.

Feel free to add another forma to fit a higher rank Life Strike, but even with an unranked Life Strike you'll likely reach max HP after 1-2 hits as you're dealing thousands of damage per attack, while your HP is at most about 1 thousand.