if I play I decided to try a different approach with the Templar this time, developing the Armour + Energy Shield defences which are naturally emphasised by also incorporating Zealot's Oath and the life regeneration passives near the Templar starting area. This means, rather than emphasise the 'magic' abilities from transitioning into the Witch's tree, either venturing into the Marauder's (strangely enough I've never incorporated skills from along this area) or perhaps even diverging into the Scion-Duelist route. So usually it is a Templar with 'Witch' secondary passives, making for something of a melee class with 'magic' passives, but I might try incorporating the Duelist's skill tree, or more simply the Marauder's. I will have to count passives again to see how that all fares.
I'm also still fixated on Cast on Melee, I know this has to work and I think my recent potential discovery of Whirling Blades decoupling the cast limitation of certain spells (e.g. four creatures 'on cast' but only one cast of Arc etc) could make things very interesting. However I would need to actually verify that possibility and then see which spell or spells warrant specialisation with an alternate skill to activate said spells. Another point of interest is the noticeably increased spell power that comes from the Cast on Melee gem, approximately 77% at level 20 by memory, which makes some spells especially powerful, e.g. Molten Shell.
the other point of interest is that I believe Cast on Melee also bypasses any spell cooldown timers, such as with Cold Snap, so this makes for a reasonably powerful combination in circumstances where the use of that particular spell or others would exceed the spell casting ability of a natural caster. One of the problems with Cast on Melee is that is usually slower than simply casting the spells, not definitive of all factors to take into consideration but a decisive one in itself, such as simply casting Arc, or Lightning Ball or whatever. However Cold Snap has a long cooldown, something like four seconds, but Cast on Melee can bypass this cooldown and (or so I believe) cast any number of generated 'on casts' (unlike Arc the spell does not originate from the caster so is not limited as with the aforesaid example with Arc). The problem..it might be kind of redundant, since I typically use Glacial Hammer unless specifically going sword and shield. Yet it is also possible this might produce synergy with Glacial Hammer's 30% shatter property and of course Herald of Ice, which I have not used to any great extent of yet.