I remember someone from the forum citing one of their players, who went like "Defensive blast is awesome, you can just keep exploding over and over again" -- so that definitely had to be fixed. Making Opp' Sacrifice incompatible was the most important rule change there.
Desperate Ward (counterspells)
Only works against sorcery, only a hostile effect directed at sorcerer. +Xd6 to saving throw where X is # of PPs spent.
Yeah it is rather narrow, but it may be a lifesaver for showdown against evil sorcerers. To widen it, I'd suggest it might create an antimagic field decreasing the magic attack bonus of any spell by Xd6. Or something like that.
Weapon Curse (curses)
Xd6 damage from weapons, spells, and other direct attacks is taken by the attacker instead of the sorcerer. Lasts one round or until damage is gone.
This seems very useful, actually quite powerful but not broken. It's also available quite early on, as first or second sorcery style.
Not This Hour (divination)
Sorcerer gains Xd6 hit points for one round.
The intent is okay but the wording may be a bit problematic, you need to treat these specifically as temporary HP that are used up first. Actually I'd change the wording to "Xd6 points of damaged are soaked for one round" or something to that effect.
Obviously, Weapons Curse is much stronger since it has the same soaking effect but also returns the favour on top of that.
Terrible Fascination (hypnotism)
Within 10' Entranced as spell. Lasts 1d4 rounds.
Hmmmm I guess this is atmospheric, but it probably can also be abused in non-combat situations. What are the PP good for? Do they maybe affect the max HD? Note that the spell Entrance cannot affect creatures of more than 6HD (or characters higher than 6th level).
Animal Intercessor (nature)
Animal makes a Reflex save against attack roll to take the damage instead. It makes one charge attack. Size = medium < 4, large 4-8, huge 9+ PPs. One attack on sorcerer's attacker unless attacked. If large enough, sorcerer can make DC 15 Reflex to leave with animal.
I share your reservations; probably its prime use would be as a getaway ride for cornered NPC sorcerers. Nature isn't such a terribly useful style for PCs anyway.
Chill of the Grave (necromancy)
10' take Xd6 damage. Fort save vs. Magic Attack Roll for half. Zombies and undead immune.
That's the one closest to the original DB, replacing Fire with Chill. Nice AoE damage dealing but becomes available only rather late, as it doesn't make sense taking Necromancy style before level 8 or maybe 12. Of course it's great for the necromancer to use this DB without harming his own minions.
Vanish (oriental)
If the Xd6 is greater than the attack damage, the sorcerer teleports someplace nearby that is appropriate (GM's decision).
As I understand it, the sorcerer does not _take_ the damage if his Xd6 is greater than attack damage. So if normally a MDS would be necessary, a successful DB negates that damage and teleports the caster. Again, this is more useful than Not This Hour.
Blast Wave (prestidigitation)
Xd6 feet knockback, falling damage of 1d6 per 10', doubled if hitting wall/barrier, Reflex save for half distance.
Yay, I really like that one. It has AoE, it buys time, it's stylish and quite impressive. It's not overpowered since the damage is limited. And it's available very early on, since Presti is a useful style even for first levels. My favourite of the new DBs.
Master, Aid Me!
Need demonic pact. Demon shows up immediately within 10' and can act immediately. It can Reflex save to take damage from attack on sorcerer. Hangs around one round per PP or until banished/slain. Gives a corruption point. Greater demonic pact enables summoning multiple demons.
Oh yeah, that's quite powerful. Imagine the Sorc casts this with 9PP -- having a demon around for 9 rounds is no fun at all. But what's more interesting: what if the demon is actually slain during this period? Is it really dead and gone? If so, this DB seems to be a good way to get rid of a demonic pact if the sorcerer so desires.
Also, the standard issue Pact Demon would be a Black Fiend who won't have more than ~40hp anyway. The Physical Immunity is of course a problem. So that may be a powerful DB for lowlevels, yes, but it will rapidly lose its terror from early-mid levels on.