NPC Weapon List

Just Remember:
Safe two-handed (no AoE weaponskills): Great Katana or Great Axe or Polearm
Safe one-handed (no AoE weaponskills): Axe or Katana or Club

• Luto will accept these after the first six calls or so (from Allakhazam).
• The best weapons seem to be Uchigatana (Great Katana) (highest level weapon, highest damage, and lowest delay, most expensive, and easiest to skill chain with), Claymore (Great Sword) (mid-range level, damage, delay, and priced), and Butterfly Axe (Great Axe) (low level and priced, but high delay).
• Trying to trade two Kunai (Katana) for dual wield will not work. The NPC will just use a Kunai and a shield.
• August 18th, 2005 Edit - I strongly recommend that you do not give your NPCs a Staff. NPCs will use the AoE weapon skill called Earth Crusher which may get your NPC killed.
  

• Luto will accept these after the first twelve (could be more, could be less for some people) calls or so (from FFXIOnline).
• The best weapons this time seem to be Two-Handed Sword (Great Sword) (highest level weapon and damage, relatively low delay, but most expensive), Tachi (Great Katana) (low level and damage, but low delay, least expensive, and easiest to skill chain with), and Greataxe (Great Axe) (mid-range level and damage though high delay, but mid-range priced).
• Same deal with Wakizashi (Katana) as Kunai for dual wield. The NPC will just use a Wakizashi and a shield.
• Yes, some of the second stage weapons are retrogrades as oppose to upgrades.
• August 18th, 2005 Edit - Be mindful that some weapons offer AoE weapon skills. A quick list includes Spinning Attack for Hand-to-Hand (Mnk 49), Cyclone for Dagger (Thf 41), Circle Blade for Sword (Pld 49), Shockwave for Great Sword (Drk 49), Spinning Scythe for Scythe (Drk 41), and the aforementioned Earth Crusher for Staff (Pld 23). Keeping the weapon until your NPC reaches the level of the job that can use the specific weapon skill is fine. But, keeping it after could get your NPC killed. This means that Great Katana, Great Axe, Polearm, Axe, Katana, and Club are safe to give NPCs without having to worry about switching.
• August 16th, 2005 Edit - A recent discovery in the second weapon upgrade cut scene is that Luto will accept shields as well as weapons. It is possible this shield option is only seen by those whose NPCs are Shield types or were given a one-handed weapon for their first upgrade. Of course, NPCs cannot use a two-handed weapon plus a shield. If you trade a shield that Luto will accept after trading a two-handed weapon, the two-handed weapon will probably be lost. Currently, the only known shields Luto will accept are Lauan Shield (level 1) and Shell Shield (level 7) (from FFXIOnline).
  

NPC 6th Weapon Upgrade (Thanks to wiki.ffxiclopedia.org for info)

NPC 7th Weapon Upgrade (Thanks to wiki.ffxiclopedia.org for info)