Thoughts after finishing and trying out different things

Pretty much this.  When you look at any weapon, you have to consider its damage per second (dps) and secondary attributes.  This includes things like the area it hits.  In most cases its dps is the most important stat.  In SotN, I used the basilard for way longer then it should be used because its dps was so high.  It was lacking in range and damage per hit, but you could hit so fast, it made up for it.  The boots do that to an extreme.  Add in the combo and allowing sliding to be an attack and you have the strongest weapon in the game.  That combo, also allows you to get more range when jumping, which is another large plus.

Two-handed weapons can be very good, but require you to do cancelling maneuvers.  Either by jumping or backdashing.  I can do both, but prefer not to on a first playthrough when I am just trying to have fun.  This means their only benefit is the size of the area of their attack since their dps is so low.

There is one exception to that last comment.  The katana line has two special attacks.  One works like the boot's special, but cannot be used in the air.  The other is done with a foward, back, forward, attack input that you then charge for a dash attack that does a good amount of damage and moves you a huge amount.  The downside, 50 mana.  It is very cool, but doesnt consistently allow you to cross gaps.

So yeah, slow weapons are pretty weak right now unless you are doing a pretty specific set of tricks with them.  If those tricks are removed (which if the previous igavanias are to go on they wont be), then in their current form, there is no reason to use the,.