Soldier of Hell: Eh.
Tutor of Witches: Magic, and selling magic, is always nice. (125 points)
Lord of Demons: Situational use, meh.
Trader of Favors: Useful, and also the name of the game. (80 points)
Walker Among Worlds: Awesome, but impractical. It would take up most of our DP, and it only helps if we can find cracks to useful worlds.
Name of Liege: Maybe if we have some spare debt. (5 points)
Claws: Maybe, but I don't see us getting a lot of mileage from violence. Besides, subtlety should be useful.
Horns: Heck no. Subtlety would need to be forgotten.
Demon's Eyes: Eh. We don't know how common illusions are or how far beyond the rest is. Maybe if we have leftover debt. (40 points.)
Wings: Oh heck yeah. (20 for opening the door, 60 for the whole package)
Sword: Useful, if we don't run out of debt. Inconspicuous but deadly. (15 points)
Clothes: Unless we run out of points, very useful in blending in. (5 points)
Spell Book: Spells are good. (30 points)
Witch's Blade: Ditto. (25 points)
Mortal Husk: Eh.
Indebted Imp: Potentially very useful indeed. (40 points)
Writ of Transit: Expensive for a one-shot deal.
Stone of Hellstuff: Hm. Potentially quite useful. (10 points)
Bag: Dull.
Tutor of Witches is useful enough, between that extra bit of magical lore and the ability to grant others magical knowledge/power more easily, to warrant half our debt. Trader of Favors is also quite useful. Throw in a spellbook and sword, and we've spent 250.
If we want to drop the name-drop, we could instead get wings, the imp, the name of our lord, the sword, and clothes.
If we don't want magic and just want to be a trader, clothes are a must. The sword is, of course, always useful. Aside from that...an indebted imp, um...the eyes, the wings, the rock?
But, cooperation (+1's) are how you get good camaraderie and a good chance of getting the majority desire.
Tutor of witches
trader of favors
name of liege
spellbook
stone of hellstuff
total points spent: 250
don't see any reason to waste points on passing conveniences.
+1, it has the important stuff.