[Metuluzian]

Is there any table of the weapons, with a gradation, and where you can see what kind of bonuses which gives?
Ive no idea about accurate, surpassigly, eminently, exceedingly, superior etc. Any database?
Or something about Diamond katana, for example.

[allsuperior]

http://www.uoguide.com/Item_Identification

That page says what you need. As for diamond katana this page is what you are looking for:
http://in-uo.net/info/skills/blacksmithy

[Metuluzian]

thank you, mate!