Mandalic Stab's Pre-adjustment tp bonuses are still lower than Rudra's Storm's Post-adjustment tp bonuses. It's even weaker considering it gets 60% of dex while rudra's gets 80%, and the attack modifier doesn't give an advantage since parties are set up so everyone has capped attack all the time.
What it would do is make Madalic the better weaponskill when using Vajra as well as giving thf a better skillchain option for light.