When you can utilize Word of Crota, it's a chain killer for even the toughest of enemies with the void damage modifier on.
The reason fatebringer is getting the attention is for two reasons:
#1. People like firefly.
#2. HoW will eventually feature a raid and we all know the Fallen main enemy weakness is Arc.
To be fair? I can utilize all hand cannons quite easily and find Word of Crota is much better then Fatebringer due to the fact it chains kills for headshots and a higher stability rating. Explosive rounds is fun to mess with people, but the simple enough statistics build says it all about Word of Crota:
Higher Rate of Fire, Range, Stability, and Reload with the potential for an additional kill every three headshots and a 12 ammo clip. That's 3 kills if you are terrible at body shots naturally with a 5th thrown in for the steady headshot multiplier AND two shots can be missed.
Again, if you can line up the headshots? Word of Crota is hands down the better gun. Most people don't line up headshots or dying to TLW or Thorn most of the time though...