Melee / mage build questions

So having played through a while, there’s some things that I still don’t know and I need answers. For context as this may affect your responses…

Dual wielding katanas (moonveil and uchi) with Carian regal sceptre. Wearing Carian knight armour.

60 INT / 27 VIG / 23 END / 27 MND / 18 DEX / fuck all everything else

• what levels should I increase from here for a strong mage / melee build?
• Does anyone use a shield with this type of build? I usually thin the crowd out with spells then just go in dual swinging and either succeed or die instantly
• what is the best armour for this build?