Spellblade support gem for two-handed weapons?

Why is the support gem only for one-handed weapons?
Wouldn't it be possible to have it work on two-handed weapons as well with a penalty to it?

The reason why I am asking this is because I am doing an energy blade build and I would love to lean on a two-handed playstyle.

You can build around Battlemage instead. If you don't plan to use crits, you can use Cadigan's Crown. Or play Inquisitor.