This page of our guide to Wolfenstein Youngblood solves the rather simple problem of not being able to pick up weapons lying on the ground. This does not apply if the sister has all the resources and cannot take more ammo with her.
The problem concerns heavy weapons, which in most cases are used by oncoming super-soldiers (enemies in very large armor). Even if you can defeat an opponent who used such a weapon, you won’t be able to use it on your own.
The solution to this problem is to unlock at least one ability related to the use of heavy weapons. The first such skill is Bigger Guns from the Muscle category. It costs 4 skill points and allows you to pick up heavy weapons that have been dropped by defeated enemies.
The second skill is Extreme Gun Pocket from the Muscle category. Requires an upgrade to at least 20 experience and an additional 6 skill points. This ability allows you to store heavy weapons in your inventory. This way you won’t have to discard heavy weapons after you run out of ammo or when you leave the map. That’s not all, because the game also allows you to upgrade the heavy weapons you wield.
From the moment you unlock at least the Bigger Guns skill, you can find an interactive heavy weapon – in the example above, it’s the Laserkraftwerk laser gun. Heavy weapons, in addition to their high damage power, are also useful for destroying blocked passages.