The max level for assassins is 15 (Grandfather of Assassins) - but Iuz is level 16.
Fighters and paladins get 3/2 melee attacks/round at 7th level, 2 at 13th level, but rangers get 3/2 at 8th level and 2 at 15th level.
I think that all fighter-types can sweep puny creatures up to their level.
Player's Handbook:
Thief: club, dagger, dart, sling, sword (short, broad, long).
Unearthed Arcana:
Thief: bow (short), caltrop, club, crossbow (hand), dagger, dart, garrot, knife, sap, sling, sword (broad), sword (falchion), sword (long), sword (short).