Leviathan is ok.. not commonly used at 5* since people prefer the specialized weapons. You could try the Brandish line to see if you like that better. Some people prefer Divine Avenger, etc.
Definitely don't bother making Azure Guardian. It's outclassed by the Wolver armors, or you could make armors with other types of defense that might be more useful.
inb4 get Chaos and Swiftstrike
Flowchart is giving you the correct general advice, and Blake-Sky-Blade is right in asking for more information. My detailed sword guide may help you with the basic ideas, how to categorize your options, and how to refine your questions in this thread.
I actually really like leviathan blade, I use mine all the time. It might not be the strongest swords, as Bopp points out with his guide. Azure guardian is generally regarded as a terrible option, and is at 5*, outclassed by everything else ever. But leviathan blade is nice to have.
If you're interested about comparing Levi to its emo cousin, CIV, have a look here.
This about sums it up: http://www.youtube.com/watch?v=FwiYNYlqJL0
If you know you....
a. Don't plan on getting too far into the weapon class
b. Want a cheap, effective way of reaching t3 with general purpose gear, aka seeing the same weapon every godforsaken floor
c. Are a bomber
d. Generally don't give a ...
Get normal weapons.
If you are not going to get many weapons and just want to reach tier 3 and do most levels fine without the efficiency specialised weapons have, having both Leviathan and Valiance is a really good combo for having two slots.
But no Azure Guardian, really. You are better off with skolver, boosting damage of your sword, while sacrificing a tiny tiny amount of the same type of defense for freeze resistance!
CiV has served me well, also. It all depends on the types of monsters you like getting close to.
The problem with the CiV is that if you're going to make a weapon specifically to fight undead, you'd be better off with an elemental sword, such as a Brandish or Divine Avenger. Normal damage weapons aren't underpowered, per say, but some of their roles can be better performed by specialized types of weapons. Not to mention, the large majority of enemies in tier 3 are weak to, or at least neutral to, elemental damage.
CiV is more of a style item than one that has unsurpassed usefulness.
Well, to give you an answer, I-and most other forum peeps-will need some quick info on what weapons you like to use, which ones you have now, etc.
Alright?