I use a staff wielding battlemage and a wand and shield cleric to draw out aggro from my enemies.
If I had decided to put shield and wand on my battlemage to make him the dedicated tank then itemization and stat management would have been a nightmare.
I would need 1,maybe 2 points in Polymorph to be mobile in combat,then 1 more in Warfare for Shield Toss but getting Batering Ram would be no good because you can't cast that with a wand equiped.On the other hand you can cast Bull Rush with a wand equiped and deal physical damage to apply that Bleeding debuff.
A custom character with points in Necro,Polymorph,Hydro and Geo can be a force to reckon if you get lucky with the items. Stats used wouble be Con for Shield equip, Str for armour equip and int to further increase the power of Necro,Geo and Hydro skills.