Sorcerous tools and substances count as sorcery, certainly. Also, the rule that making mundane attacks removes Terror doesn't applies eg to dominating someone, forcing him to come to you and kneel, and then cutting his head off with a sword. This is certainly a sorcerous attack for the purpose of terror, although the sword can be completely nonmagical.
As for DC - if you think 10 + 1/2 Scholar level is too low, you can add Bonus:
Bonus equals the highest of the following
- Charisma bonus for independent scholars or scholars who serve a demon in secret
- Charisma bonus + 3 for scholars with a powerful master, or who openly serve a demon
- Half of Corruption
- 1/10 of Reputation
And, obviously, like with other Terror of Unknown tests, if you make a save for a particular sorcerer, you will never be afraid of him.
Independent sorcerers should have also a number of death-curses, along the lines of the Curse of Yizil, but suited also for non-spellcasting targets.
The most powerful curse would be, I think, an authentic Norse curse, the curse of Glam, from the Saga of Grettir the Strong:
http://omacl.org/Grettir/gr32-48.html
"At the moment when Glam fell the moon shone forth, and Glam turned his eyes up towards it. Grettir himself has related that that sight was the only one which ever made him tremble. What with fatigue and all else that he had endured, when he saw the horrible rolling of Glam's eyes his heart sank so utterly that he had not strength to draw his sword, but lay there wellnigh betwixt life and death. Glam possessed more malignant power than most fiends, for he now spoke in this wise:
"You have expended much energy, Grettir, in your search for me. Nor is that to be wondered at, if you should have little joy thereof. And now I tell you that you shall possess only half the strength and firmness of heart that were decreed to you if you had not striven with me. The might which was yours till now I am not able to take away, but it is in my power to ordain that never shall you grow stronger than you are now. Nevertheless your might is sufficient, as many shall find to their cost. Hitherto you have earned fame through your deeds, but henceforward there shall fall upon you exile and battle; your deeds shall turn to evil and your guardian-spirit shall forsake you. You will be outlawed and your lot shall be to dwell ever alone. And this I lay upon you, that these eyes of mine shall be ever before your vision. You will find it hard to live alone, and at last it shall drag you to death."
Until the character manages to get rid of the curse, which can be difficult, he suffers the following penalties:
- cannot gain new levels
- penalty of -2 to Will saves,
- when trying to walk alone at night, must make Terror save - he sees the ghost of his enemy. The Terror save must be made once each night, when alone. When in company, doesn't have to make Terror saves.