I started playing Monster Hunter 4 Ultimate recently. Being a primarily sword & shield user in previous iterations, I wanted to give the Charge Blade a try, as it seems to get most of the benefits of the S&S and add in a better source of damage with axe mode.
I understand the basic concepts of using the Charge Blade; charging phials in S&S and expending them in axe mode. However, on one hunt (probably due to some accidental button press), my shield started glowing red. Why/how did this happen? Are there any differences to fighting with and without this effect, damage-wise or in combo progressions?