I've used a CLW wand in combat. I disallowed quill blast before I thought it was broken, because it's lame (IMO). Like, freaking dance of the unicorn lame.
I don't like the vigor spells 'cause they're a pain to keep track of.
IMO a conjuration spell that created a real thing that ignored spell resistance should be subject to damage resistance, I think that is how I'd rule IMC anyway.
I also think that damaging conjurations should not scale so similarly to evocations. They should mimic environmental effect, albeit often bizarre and extreme environmental effects. Melf's Acid Arrow is very similar to being directly hit by some acid. A conjuration fire effect might be to create a real roaring bonfire in an area for a round or more.
AFAIK, conjuration (creation) spells create real stuff. which means you can neatly pick up the remains of the spell (within reason) and whack someone with it (as an improvised weapon). Comet Fall from CD is a nice example here. It creates a "real" some-hundred pounds ball of rock and ice right in the air. from there on it behaves like any other "object" subject to gravity. Where it lands, it creates a pile of rubble. REAL Rubble. Where it a conjuration (summoning) spell, this might not be the case. And if you hit someone with a rock, what type of damage would that be? Bludgeoning, I would say. So simply apply any DR not foiled by Bludgeoning Damage
Concerning spells that clearly state the type of damage done, such as ...uhh... nothing specific comming to my mind right now..., why do you think wizards would bother writing it down explicitely if you weren't to apply DR to it?
"Ya know, it's slashing damage, but sort of "special slashing damage", so it just penetrates your >Armor of Keeping of Sharp Blows<"