This forum is to be used for all discussions pertaining to Black Isle Studios' Icewind Dale and its Heart of Winter and Trials of the Luremaster expansions.
Spells fail if you get hit in combat. Neither shield, helmet nor bracers should affect spell failure. Perhaps it's one of the mods you installed? I faintly remember a mod that made spells fail if your INT wasn't high enough.
Right Speech has four aspects: 1. Not lying, but speaking the truth, 2. Avoiding rude and coarse words, but using gentle speech beneficial to the listener, 3. Not slandering, but promoting friendliness and unity, 4. Avoiding frivolous speech, but saying only what is appropriate and beneficial.