No. Glancing blows are part of the one-roll system that determines hit, miss, dodge, parry, crit, glancing, block, etc.
There's no way to reduce glancing blows once your weapon skill is capped. At all.
25% of your white attacks will be glancing blows, regardless of what you gear or gem for.
Basically, dodges, parries, blocks, misses, glancing blows, and crits are all part of this one-roll system in addition to normal hits.
If you ever reach a crit rating where 100% of your attacks result in a dodge, parry, block, miss, etc, then you will never see a normal hit, as it will be a glancing blow.
The ramifications of this are the following: increasing your Expertise (i.e. reducing the bosses' chance of dodging or parrying) will result in less of your attacks being glancing blows (sorta).
What I mean by "sorta" is that you'll still have a 25% chance to get a glancing blow, but you're removing dodges from the attack table (since you can't get parried from behind, and bosses don't block).
What does this mean?
It really doesn't mean anything for us. I'm guessing 90% of the posters on these forums don't know this info; it has no real baring on how we DPS, as it's an unreal amount of crit rating that you'd need to get to the "crit cap," and there's no reason to socket for crit rating, as it's probably our weakest DPS stat. Glancing blows will happen, and there's no way to reduce them.
It does sorta explain why Expertise is so damn good, though.
Edit: WoWwiki has a pretty decent article explaining it. http://www.wowwiki.com/Glancing
Edited, Jun 9th 2008 2:07am by Theophany