Anulus Connectens: Andreva of Jerbiton

[Erik_Tyrrell]

I just fit a unervingly large proportion of my "what I want to do with this character" notes into less than 20 seasons of labwork. I'll have to brainstorm some more stuff for her to do (a familiar might be a worthwhile project).

Here is a spell that Andrevea can knock out in one season. Some of the other spells are based on this one so I very much want to get this one right. I'm sure that I've seen its like before but I believe that it was for fourth edition. If any of you are aware of a relevant fifth edition example please let me know.

Insubstantial Duelist
ReTe 25
R: Voice, D: Diam., T: Ind.
This spell is cast upon a target sword or knife. The target blade will then fight under the direction of the caster as if wielded by a person of average height for the duration of the spell. The caster is able to choose the blade's initial target when the spell is cast. During the spell's duration the caster my direct the weapon to pother targets using a vocal command. The combat totals of the weapon are generated as if it had a wielder with a +4 strength, a dexterity of +2, a 0 in all other attributes, and a weapon skill equal to the higher of the caster's finesse -3 or the caster's appropriate weapon skill -1. If the weapon is thrown to the ground sufficiently hard the spell will end prematurely. One way to do this is by an attack roll against the sword's defense total (adjusted for the sword's size) that does +15 or greater damage. Andreva's sigil expresses itself in this spell by having the sword continually perform spins, flips and flourishes when it is not in combat.
(base 3 +2 metal, +2 voice, +1 diameter, +1 increased strength, +1 increased dexterity)

Is this the best way to generate totals?
Is it appropriate to include a method to defeat the spell? Is it believable? Would it be better balanced without one?
Are the extra magnitudes for increased Str and Dex appropriate? Should the amounts of added strength and dex be different?
Do I need a higher base level than "very unnatural movement "to have the sword more or less think for itself when it comes to attacking a target?