I know this thread is a month old, but I've just read through the Common Magic rules, hit on some of the same issues raised in this thread, and have a few relevant comments and suggestions.
From even a very careful straight reading, it does appear that fate is overpowered compared to Armoursmith's Boon, Bandit's Cloak, Bearing Witness, Entertainer's Smile, Goldent Tongue and possibly others. Fate is clearly far superior to any of them by a very large margin. I can see several feasible fixes that might introduce some of checks and balances. 1) Make Fate a 3 point spell that gives a fixed +/- %20. 2) Make it a +/- 5% per point. 3) leave as-is but the opposite modifier is applied to the caster's next skill check, or the skill check after that if the caster is the target.
Bladesharp not limited to 4 points? Ok, safety catches are now firmly off in this edition of Runequest. As we will see, this is a recurring theme.
Speedart is now crap in most common combat situations because being one-shot only you get so little bang for buck compared to Bladesharp. The exception is for sniping against unprepared targets, in which case it's massively overpowered (Speedart 6 anyone?). Runequest snipers just got handed the equivalent of a Barrett Light 50. The way it worked in the old days meant it gave good bang for buck, but could not be abused because it was a fixed-return spell.
Love Hand of Death. Great for sinister martial artists.
Disruption is progressive? Nasty. Interesting. As I said, safeties off. Bladesharp is no longer a handy occasional zap spell, but is a souped-up magic hand-grenade. I'd make Disruption Resist (Persistence) because it's a purely magical attack, and it would introduce an interesting dynamic between this, Frostbite and Skybolt which is already Resist (Evade).
Frostbite seems pretty nasty too. Definitely hand-grenade territory. I'd keep Frostbite Resist (Resilience) as you're resisting a physical effect, see Disruption above.
The only Common Magic spell that helps defend against spirits is Spirit Bane, and it's of very limited utility. Having at least one decent spell to help defend in spirit combat or protect against being discorporated would be a big help. I haven't read the spirit magic rules in depth yet, but I'm concerned that most typical parties are just going to get blatted by even moderately organised spirit magicians. More on that in an appropriate thread when I have read those rules more completely.
The old RQ3 versions of most of these spells were better thought out and less game breaking. The fact that character's don't have General Hit Points nowadays I suppose makes them more resilient to multi-location damaging spells, but still...
In some ways this edition of RQ has a crazy, no-holds-barred, daring edge to it that is attractive. It does remind me of the old RQ2 in this respect. RQ3 was much more constrained and balanced, but actually not quite as much fun. It'll be interesting to see how this edition works out in play.
Simon Hibbs