Add an option for 2-handed weapons to deal less damage when held in 1 hand

[nazarovtr]

For now using an atgeir in one hand is way too overpowered. Very long reach and high damage. In vanilla it is compensated by slow and awkward animation, but with VHVR you can pretty much treat an atgeir as an extra-long one-handed sword.
2-handed warhammers are also OP for the same reason.
Maybe 1/3 of the original damage is a good value?
Maybe turn this option on by default?