The blood contains our DNA, which is a unique genetic signature. This shows that you sincerely want to enter this path to become a divine being in the future.
"Blood Sacrifices Explained: Our Gods And "Their Gods" [Updated]" by HPHC:
https://ancient-forums.com/viewtopic.php?p=372474#p372474
There's a big difference between putting a tiny drop of blood into a sacred pact than using it for reasons the jews do as in raising negative and destructive energy in a complete parasitic manner.
In addition to these other replies, this is basically just giving your signature in a sample of your own DNA which your blood contains, making it real and binding to you. As others have mentioned it is in no way connected to death or other things like the taking of life. This is the only time blood will be used for any thing, besides perhaps rune consecration, but this is an optional method and runes do not really need blood.
Other than the dedication ritual, we do not encourage anybody to sacrifice their blood or ANY blood. In fact you do not even Sacrifice your blood, but make a commitment with it, This is different from, if you would sacrifice your blood to a demon in return of something.
Other false Satanist usually do sacrifice their blood or in very bad situations, even someone else's blood. WE DO NOT SUPPORT THIS IN ANY WAY, AND THE GODS DO NOT ACCEPTS BLOOD SACRIFICE.