This looks like something that may well have been addressed already, but here goes.
Can a level 2 titan mauler barbarian/level 1 magus use a great sword, falchion (or normally two-handed weapon) in one hand with spell combat?
yep spell combat just requires a free hand, so it works
you giving up alot for an extra d6 though but if it fits your flavour go for it ;)
this combo would be more interesting using a 2h reach weapon 1h