If your only problem is the fiery area with the Blood Stone, then you don't need tenebrium weapons to clear it.
Since you have a rogue in your party, then you can take the left path towards the Blood Stone and walk in shadow past the Immaculates there (you can also win the argument to render them neutral). You'll come to the teleport mirror which will take you closer to the Blood Stone. Then, there is another group of Immaculates with a few demons who have the aura of the Void. Again you can walk in shadow past them. Once you are in the vicinity of the blood stone, teleport the rest of your party to the rogue (don't go too close to the stone though since for some reason my rogue was dying if he tried to attack the stone). Any of the ranged attacks or spells can now be used to destroy the blood stone. I used a normal bow to destroy it if I remember correctly.
The portals in the homestead will then start to get opened again.
