Funny, I was just thinking about creating a thread today based on multiclassed PrEs....
Spellsword I
AP cost: 4
Requirements: Wiz 4 or Sor 4, and any one of: Pal 2, Ftr 2, Barb 2
Spellsword I removes the arcane spell failure of any medium armor you may be wearing, including Warforged's Mithral body. Additionally, you gain the "Spellsword Imbue I" ability.
Ability: Spellsword Imbue I
Imbues all melee weapons that you equip with arcane force, granting them the Force ability (+1d6 Force damage) and negating the incorporeal miss chance of ethereal creatures. This ability costs 10 spell points to activate, and triggers a lengthy cooldown of the Magic Missile spell. Only one Spellsword Imbue ability may be active at any time.
Spellsword II
AP cost: 2
Requirements: Wiz 10 or Sor 10, Enhancement: Spellsword I, Proficiency: Heavy Armor
Spellsword II removes the arcane spell failure of any heavy armor you may be wearing, including Warforged's Adamantine body. Additionally, you gain the "Spellsword Imbue II" ability.
Ability: Spellsword Imbue II
Performs a melee attack with a ball of fire that detonates on impact, causing an explosion of flame that deals 1d6 per caster level fire damage (max 10d6) to the target. This only affects the target, and does not affect nearby enemies. A successful Reflex save reduces the damage by half. Use of this ability triggers a lengthy cooldown of the "Fireball" spell. Only one Spellsword Imbue ability may be active at any time.
Spellsword III
AP cost: 2
Requirements: Wiz 16 or Sor 16, Enhancement: Spellsword II, Proficiency: Tower Shield
Spellsword III reduces the arcane spell failure of tower shields you may be wearing to 20%. Additionally, you gain the "Spellsword Imbue III" ability.
Ability: Spellsword Imbue III
Performs a melee attack with a blast of fire that detonates on impact, causing an explosion of flame that deals 1d6 per caster level fire damage (max 20d6) to the target. This only affects the target, and does not affect nearby enemies. A successful Reflex save reduces the damage by half. Use of this ability triggers a lengthy cooldown of the "Delayed Blast Fireball" spell. Only one Spellsword Imbue ability may be active at any time.
the second and third tier imbues both act like deepwood sniper's ability, while the first acts like arcane archers. Using 2nd or 3rd tier will deactivate the first tier (though it can be reapplied) Additionally, the Imbues could be listed as seperate abilities, like force arrow, allowing for each elemental type to be purchased.