Usually, everything else being equal (but everything is not always equal, lol), lower modulus graphite blanks will be a little tougher........ so something like 33 million to 38 million modulus, something like IM6 rather than IM 7, will be slightly more rugged.

 

But generally, graphite rods are fragile....... the manufacturers make them as thin and sensitive and light as possible.......... and supposedly, most of the strength is in the outer wall of the blank.......so if you nick/cut the blank, it could easily be a weak spot ready to break. 

All rods stress more fibers on the outer diameter than in the middle, that is why even the high performance bamboo rods were hollow. The rest is dead weight with lessening stresses on it till you reach the center which has virtually none. You really didn't think the new skinny, thick wall blanks were more aerodynamic? Just how wind resistant does the big end close to your hand have to be? You may have exactly the same weight and material in a brandy snifter and a beer mug, which one will survive a fall? Take a look at the St. Croix rod, to get the power they needed they increased the diameter, more power, less glass and weight to get there. Wasn't long ago people were complaining about the slight weight difference increases of the thin diameter, heavy wall design of the Graphite USA rod blanks, even though they were the only all graphite rods out there that have survived decades of hard saltwater use, including rail rod use and not blow up, now they flock to them from others because sales speak tells them they are sleeker, more stylish, you wouldn't want to mention they are heavier and warranty returns dropped because of it. They haven't gone to the GUSA layup so they are not as durable still. There is a reason why the fantastic Point Blank blanks are all larger diameter, light, responsive blanks.

You can graph it simply, draw a circle using a quarter, now make a pie graph out of it, any angle, now drop a dime in the center. You now are looking at the difference in action fibers activated by deflecting two blanks those diameters at that angle. It's not linear as you can see, it's exponential because of Pi, all math is effected by 3.1416 when messing with circles.