Samurai Saber

In Kung Fu every "sword" that only has one sharp edge instead of being sharp on both sides of the blade is classified not as a sword, but as a "knife." In some more recent films you see the basic saber translated in subtitles as "machete" instead of "broadsword" and it is more true to the culture. Though few people in our modern world care enough about this subject matter to realize it, we see the same distinction in English between swords and "sabers." The katana isn't so much a "Samurai Sword" but a "Samurai Saber."

Note for example the similarities between the Katana and the "Tai Chi Saber":

It's no secret that I am a big fan of the Tai Chi saber, but I have also mentioned that after my 1st year of Aikido my training was mostly with the Bokenjitsu as practiced in Aikido, focusing on Aikido strategy with improvised weapons. This sort of Bokenjitsu though infantile in its technique, is fast to learn and easy to use, and can challenge more advanced technique. Here is me (and someone who trained with me in the same Aikido and Arnis classes that I took) using this technique in a snow storm (integrated with some one-handed Arnis):

This basic Bokenjitsu as practiced in Aikido has very simple technique, which could be used with a weapon as simple as a baseball bat. If you imagine fighting with a base ball bat, but instead having a strong focus on keeping the bat between you and your opponent (instead of having no weapon to block with if you miss,) you very quickly get your basic Katana attacks:

For stance and footwork I am not going to get into the complexities of the Aikido footwork and how that is applied to self defense, I will instead here recommend that you use whatever sort of front stance you are used to using, as long as it has your hips or shoulders facing head on or 45 degrees to the opponent (you don't want to do this from a side stance, but a cat stance could work, a front stance is better.) You can see the front stance is commonly used with the Tai Chi Saber and it can work regardless of where you got your front stance from (as long as your front stance is not too deep, it has to be a front stance you can use in free sparring.) If you want to really have Aikido flavor to  your fight, you should rely primarily in side stepping rather than lunging towards and away from your opponent:

For defense, this is the main drill you should practice, which is delivering those clean overhead attacks (which defensively turn into blocks when needed,) blocking those clean overhead attacks with upside-down "roof" blocks, and countering with more clean overhead attacks:

For sparring equipment, I strongly recommend getting "padded katanas" from Nihonzashi. Note: these weapons have a solid (not flexible) core and canvas as a skin, making their over all weight slightly heavier than a boken, about the same weight a real steel sword! This construction design should be easier to reproduce than the nylon & fiberglass sparring weapons of the past while being also far more realistic as far as technique goes: