I don't know if this has been confirmed anywhere but the way I see it is that the sword is a holdover from the time when Androids 19 and 20 were expected to be the actual villains of the story, and rather than using ki attacks Trunks used a sword to attack them.
It's funny that people are having to remind Jeff and Dan that Dragon Ball Kai The Final Chapters is part of DBZ since it was separated for the Kai production despite being the last stretch of episodes in DBZ, because that's the exact same thing which happened with the adaptation of Dragon Ball from its manga to the TV series. They chose an arbitrary point to divide the show into two parts for marketing reasons. As far as the manga is concerned, it's all one story - from when Goku met Bulma until the end of the Buu arc.
I've always liked the term Artificial Human because of how many different types there are. You have cyborgs who started off as humans (17, 18 and 20), fully mechanical units like 19 and 16 and the fully biological android Cell. Dr Gero really was a genius.
Xel's comments