Flowen's 3084 is the best sword (Sword of Ultima is technically better if you can get it and add Charge but it definitely needs a buff) IMO, apart from DF, and I've had them all. Zanba can be a liability especially solo. I can agree though, HUs definitely need more love. I don't use dark weapons and I'm very effective solo. People look over certain weapons for HU that can make them a nightmare.
Charge Vulcs
Daylight Scar
Black King Bar
Musashi (definitely overlooked)
Jizai
Galatine (most overlooked weapon on this list probably that can do MASSIVE damage)
Flowen's AUW-3084 (Seriously guys, if you knew the virtues of this weapon... A H-S-S can deal 4,000 easy with NO percents bonus against the enemy(ies) from the weapon.)
You don't need the most top tier weapons to be effective, just a little ingenuity and willingness to learn.