When it comes to consuming souls and taking over their abilities, Alice wasn't strictly limited to drinking blood.
In the right scenario, she's able to do so with attacks.
Of course, the success rate of this was a lot lower not to mention the inherent risks of facing an attack head on hoping she had the resistances to consume it without injury.
But when it comes to a direct soul attack, Alice needed a method of locking down her enemy. To prevent them from running away so that she could digest the power and take it for herself.
Folding her arms, Alice opened her mouth.
"Let's set aside how I can attack souls. What if they try to run away? Since they decided to enter my soul, I want to use something to keep them there." Alice asked.
If they simply overload her soul then run away, they would've achieved their purpose even if Alice had the option of fighting them.
But if she were to trap them, she'll be able to fight on her own terms rather than subject herself to the enemy.