What I've notice is that the mutations and horns and spikes really bring out the Word Bearer qualties. I like how you have taken advantage of the mutations.
If you look at the pictures; the first looks very awesome, then you go to the second, and this is the one that kind of just looks boring. for some reason the normal look doesn't seem to look good on the Word Bearers. I'm just saying it from perspective. Then the third one just looks fantastic. Out of the pictures so far, I'd say that this one looks the best. It looks like you replicated it from ADB's novel The First Heretic. The terminator does enough to make him Word Bearerish with the spikes all over the armor.
I would also say the powerfist looks very well. It's interesting, but these Word Bearer pieces have really given me a different perspective on a Word Bearer Army. Most Word Bearer armies look very boring. You've done well to give them an awesome look.