I'm not sure if this was mentioned already , but if you craft a weapon like a 1H sword , upgrade it via tormented soul + whetstone , and enchant it with an essence , your enchant is significantly weaker than a tenebrium enchant. But if you enchant that 1h sword with tenebrium , then enchant it with a essence , your elemental enchant retains the same strenght as a tenebrium one.
