I'm guessing that the Spathion being 0 slot is to balance it against the Paramerion, given that the Paramerion is longer, faster, easier to use, does 1 more swing damage, 1 less stab damage, and costs nearly 4k less.
Which is retarded - no archer will ever use a Spathion, and a 1h/1h+shield will always take the Paramerion over the Spathion since it's just better. Slots don't come into the equasion. Either Paramerion needs a nerf or Spathion needs a buff.
The only possible non-archer build that would use this would be a hoplite - 2slot spear, huscarl shield and this and they could just as easily take a Scottish Sword, since that's 0 slots too, is even faster and cheaper than the Paramerion - while not doing quite so much damage.