[Crenshinibon]

Actually, the Kensai bonus does not apply to ranged weapons. You can check by equipping K'logarath +4 as a melee weapon versus a ranged weapon.

As for Kensai/Mage, yes the bonus does apply to Melf's Minute Meteors and Energy Blades.

Assassin, it's good to poison or multi-poison a ranged weapon, but the THAC0 is still pretty bad.

I never thought of a Blade as a ranged character due to its' amazing tanking ability.

I'd rank them in this order:

Archer
Kensai/Mage
Assassin
Blade

The Archer can kill enemies not only through damage but through ability drain.

The Kensai/Mage, also having great tanking ability, can provide pure damage through the aforementioned spells and Tensor's.

The Assassin can render an enemy harmless due to the constant damage from the poison (not to mention the disrupting damage animation).

The Blade can increase its' attack by one AND do full damage for a short while. At best (without using bugs), when using Gesen's you can achieve seven attacks per round at about -10 THAC0 and about five attacks per round while with Firetooth you can make three attacks per round at -13 THAC0.

Also, note that "enchant weapon effects" such as Poison Weapon or Called Shot, can be applied with area of effect through items like the Arrows of Detonation.

There are a good amount of ranged builds, yes, but the archer is still the best among them (assuming you don't abuse bugs of course).

EDIT: If you start in the original with 19 Dexterity, you can achieve 22, depending on your choices.