I've been wondering when sword fullers came into use. There are reproduced Roman Spathas with and without fullers. Were fullers used in Roman times?
I'd be pleased for any historical information.
Thanks

You can see sets of narrow groves on roman blades already in the first C AD. This is not very common, but it happens. I have personally seen the point of a blade that most probably was a Mainz type gladius that had two narrow groves down the middle. An unusual feature.

Fullers in roman swords start to occur when the spathae has reached dominance. Many types of spathae have shallow and rather narrow fullers. Not always the same number and set up on both sides either. It is rare with single fullers. You do not see spathae blades that look like slim versions of later period blades.
Cross section on spathae blades can also be rather complex. It is common with octagonal cross sections (that over time with rusting often are interpreted as diamond or lenticular!) These complex sections can also be made with groves and fullers.

So a general answer is that you start to see fullers as an integrated detail in sword design during the third C AD or perhaps even second C AD, although individual examples can be a century or more earlier (if you count narrow groves into the family of fullers).

Some Gallic swords made during the first century B.C. have double or single fullers running down the hole length of the blade. Single fullers very rare, but at least one has been found in pre-roman context. It is possible that these Gallic swords are the prototypes of the spathas that Peter Johnsson has mentioned.

You can find pictures in: Guerre et armement chez les Gaulois: 450-52 av. J.-C, Jean-Louis Brunaux et Bernard Lambot, 1986. ISBN: 2903442622 (in french, ouch!)
And JC Rapin explains their development in: gladius.revistas.csic.es/index.php/gladius/article/download/13/14 (very interesting read if you're interested in "celtic" armament, but also in french...)

Several short swords found in Ireland and believed to date before c.300 AD and definitely after 300 BC have two or three fullers.

Cheers!