In Lords Of The Fallen, the only way to level up fast in this game is to grind by defeating multiple enemies both in Axiom and Umbral. Then once the enemies are defeated use a nearby vestige and then repeat the process again. Using a vestige will reset the environment and all the enemies/ monsters you have defeated will respawn again.
To level up your character you will need the resource called Vigor, then interact with any vestige to upgrade your character. You can upgrade one of the six stats available which are:
Below you will find a brief guide on how to level up fast and defeat the first boss Pieta easily.
Lords Of The Fallen How To Level Up Fast
If you are having trouble defeating the first boss Pieta, you can just return to the way you came. Go down the stairs till you reach the Umbral Flowerbed. Climb the ladder and then go towards the right side to find another ladder. Use the ladder to go down and take the path on your right to go back to the village-like area with a vestige named “Vestige of Marco the Axe”. From there you need to clear all the enemies in the village, cross the wooden plank clear some more enemies, then take a U-turn.
There you need to visit the Umbral realm, you can see some shells on both sides of the pathway that are breakable. From these shells, enemies can spawn that will give you experience upon defeating them. Keep defeating all the enemies in your pathway and eventually, you will reach back to the Vestige of Marco the Axe.
You can use this process multiple times to level up quickly and increase your character stats. Then visit the first boss Pieta, She of Blesses Renewal to defeat her easily.