well, having a five hammer without doubt may come in hand in some cases but is not mandatory because wheel already have a splash damage type and is not affected by aoe ratio and one of the big problems with aoe atk ratio it is that it effect does not increase the aoe of skills so most of the times, trying to group mobs for a perfect smite with the +5 aoe ratio of even the god smash,may cause more problem and loss of time than simple doing the god smash and then letting the other party members kill the rest.
so the only situation where five hammer really can be of use is when farming low level mobs, where you can one shot most mobs, so allowing for a better use of the 5 aoe ratio.
and to finish with new 330 we have seems items with as high as 660 atk and once you add refinement and the new system, it will add fair good amount of damage for not only low level rank skills, but for inquisitor as well, so it will decrease the value of five hammer even more.
Tl:dr five hammer will only be useful if you can one shot everything with him, so you can indeed use those 5 aoe ratio.
side Note: too bad that imc have not add in the game a two handed club, because with the arrival of inquisitor a good two handed club with focus on P.atk would be a really nice thing to have as inquisitor who focus on p.atk damage.
