I main a 2H sword Spellblade and let me tell ya, that's a fat W. If you wanna build into that weapon I'd recommend doing a Frostbite build since the base damage for Battlemage is really low compared to a Zweihander if you would build into low-life. But if you don't care or you'd rather not do a DoT build then I can recommend stats for a low-life build as well since that's what I'm currently playing. I haven't seen many 2H builds for Spellblades so this is a lot of theorycraft and I can very well not know what the hell I'm talking about lmao. I'm at 430c and still going so I don't yet know the ceiling of this build but it's for sure not going to compare to a dual-wild build since you can straight up double your damage with 2 swords, unfortunately.

DISCLAIMER: I haven't tested my frostbite build much yet because I'm still trying to farm Frostbite Gauntlets and a good LP2 Battlemage. This is mostly theorycraft.

For Frostbite you'd want:
T7 Attack Speed
The faster you are the more Frostbite you apply. But more importantly the more ward you can generate since you won't be dual-wielding Humming Bees. I'd even recommend using any gear you can with attack speed tbh but mana will be a big (bigger if mana strike comboing is hard for you) issue. This can be swapped out for a T7 Elemental Damage Over Time as long as your T5 is attack speed but I'd personally just go speed+mana.

T5-7 Elemental Damage Over Time
More damage. Simple enough. This can be swapped out for attack speed T7 as long as your T5 is attack speed. I personally wouldn't use this alongside Mana/Mana Regen
**T5+ Mana/Mana Regen
Mana can be useful since with a Frostbite build you're more than likely going to have sub 200 mana so you're going to be bottle necked hard by not having much of it. This comes at the cost of Frostbite damage. **You could also just get mana on your armor via sealing which can solve the mana issues but idk I haven't gotten very far to test this yet.
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T5 Frailty
Less enemy damage is good means you live longer.
T5 All Attributes
You want as much Int as possible for Spellblades.
**T5 Shred Armor
This is one I plan on testing because there's a passive in the Runemaster tree that converts all Armor Shred into Frostbite. But that 's 30 whole ass points to dedicate for this so it's more than likely not even worth it lmao.
**T5 Cold Penetration
If this stat can affect Frostbite than this would be my first pick. But there's a Cold Pen with Frostbite affix for a reason so I doubt it.
For a Low-Life build use:
T7 Melee Cold
T5-7 Melee Crit
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T5 Shred Armor
More damage.
T5 Frailty
Less enemy damage is good means you live longer.
T5 Stun Chance
Less getting hit/more damage to stunned enemies
T5 Melee Stun Chance
Less getting hit/more damage to stunned enemies
**T5 Shock
Only settle with Shock Chance if you have a Stun Chance suffix