Is the Soul Geyser the most damaging spell in the game? or is there something more devastating

There are four main benefits to using the torch.

• Lighting areas

The torch can be used to light areas in the game that are dark. In addition you can light the stands as you go through the game so you do not have to travel back to a bonfire or use a Flame Butterfly

• Changing Enemy Reactions

Certain enemies will react differently if the player has the torch lit and equipped.

• NPC Interactions

Certain NPC's dialogs will change based on use of the torch. Blacksmith McDuff is found sitting on a chest, if the player uses the torch to light the stand on the other side of the room and reloads at the bonfire, the blacksmith will have moved to the other side and the chest will be free to open.

• Environment Interaction

Certain boss fights can be made easier with the torch. Using a torch to light certain environmental objects will change both the Lost Sinner and Baneful Queen Mytha fights.

Pretty sure you can't do it other than through ranking...alternatively, you can just get them offline, that's what I did.