The Royal Scimitar is the best weapon on the game. With 11-18 and 45% chance to hit + the 3 upgrades slots, that makes it the best. (The Ice Scimitar has the same stats as the Royal Scimitar. It is a 2009 Winter Event drop.) While other weapons come close, none are better. The Steel Shaft could be better but Upgrading something 99 times is very unlikely, if not impossible.
Warrior: The Blunt Weapons have a chance to Stun. While the stats on Blunt Weapons are less than the stats on Bladed Weapons, the chance to stun a Unique Enemies attack shouldn't be over looked. If you don't like to hit a tough opponent a few times and then have to heal, a Blunt Weapons and a good shield are the way to go. Warriors also have the ability Berzerker Frenzy (Player's chances to hit increase by 10% when HP is at 25% or less.) This ability shouldn't be over looked if you have enough HP.
Thief:Small Blades are good for Thieves they have abilities that make them hit harder than they look. Pinpointing can add a lot of damage bypassing an enemies resistance. Throat Slash can add even more damage and it can give you an idea of how much HP enemies have.
How hard is it to get the weapon you want? Lots of weapons look great when they are fully upgraded. However, it can take a long time to fully upgrade a weapon. 2 slots is easy to upgrade, it probably won't break. 3 can be a pain, it may break on that 3rd one a few times. Anything with 4+ will really suck, it will most likely break a few times before it's done.
The Blowfish Mace is one of my favorite weapons. It is one of the few weapons on Scroll Wars that can hit at 100% when it has 4 Voo Doo Dolls on it. It has one drawback is low minimum damage. This can make it useless against enemies with high physical resistance. It drops off of Seacilla. She has insanely high physical resistance.