As others have mentioned, it depends on whether or not the skill is defined as casted or charged up. I think a decent example is the manticore at the end of Halatali Hard. His frontal breathe and tail swipe attacks are considered charge up attacks and can't begin being executed under the effect of pacification and will be canceled if the charge up finishes with the effect pacification present. His ranged circle aoe called Fire something-or-other is considered a casting skill and can be immediately stopped by silencing it.

Pacification is handy in a few fights. I think it's pretty under utilized in general. If you time things right, you can stop nearly every skill by Diabolos with spirits, shield swipe, and shield bash.