I just think Zoro has not mastered it fully yet and thus holding back from using Enma to the fullest, how it is translated to be fair can be interpreted in both ways.
Also I think Enma at this point is far closer to a power up than a training wheel, it seems to possess it's own traits far superior than Zoro's other swords
1. Zoro hasnt mastered it and is holding back
2. Enma is a power up