Falchion (or, in latin, falx) has, through the ages, been used to describe various weapons. The dacians (enemies of Rome) were known for their forward curving two-handed pole arm-like falchions.

And even mediaeval falchions came in bigger versions.

This weird two-handed sword was (probably) called falchion as well.

No version of falchion I can recall seems finesseable. They seem to be rather crude chopping blades, possibly good for cutting through mail links.

[Edit]
Checking my 1e AD&D books close at hand I see 'Sword, Falchion' in Unearthed Arcana, clearly being a one-handed sword.
Wonder when did it become two-handed in D&D.

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