In the box p91 of HMRE: (quote) "the player does not have the option to select which ability or charact the charm affects".
You can't choose how curse your ennemy?? But, i don't see why! In SeSa, we can choose the ability.
PLus, the spell example: "dispell fortuna belli" targets expressly the single weapon ability...
So i don't understand the meaning of the quote..
Anyone can help?
At least I hope I can help. (The alternative would include me being wrong, and I'd hate that.): The first and second sentence of the paragraph belong together, meaning that a magus casting a carmen (formualistic spell) is bound by the structure of that spell to a specific attribute or characteristic. He can't choose how to curse somebody while he is casting the spell, because there is no "curse an ability of your choice" guideline. Of course, as developer of spellst or crafter of amulets and chartae he can choose which specific effect he is going to use.
As I said, I hope, I could help.
Alexios ex Miscellanea
Given as how it's a Fortunam effect it and the ability penalty is merely to simulate bad luck, I suppose it would be reasonable for the SG to simply choose the most inconvenience characteristic or attribute. On the other hand though, I think Alexios is probably correct that it refers to a different spell being required for each attribute/characteristic. Fortunately, Learned Magicans can learn spells much faster than Hermetic Magi can...
Ok so, if i have good understood, it's as all spell:
when you design your formulaic spell, you choose what it does (ignem guidelines 10 for +10 damage as a ball of flame hitting the target | curse to single weapon ).
Then when you cast the spell, you can't "change" the description (eg: using my last ignem spell to create a wall of fire doing +10 damage | using my curse to single weapon to curse great weapon) because that is a spontaneous spell doing "another thing than the one for which it has been designed.
In this way, it's more a repetition of a general rule and i understand why it's here (but i'm not convinced of the usefulness ^^).
Have I a good understanding of your point?
Well, not ALL spells, since some do allow the magus to make slight modifications (Rego spells mostly). But yes, I think that the section is probably just restating that a single spell can can only affect a single Characteristic or Attribute.
There was confusion among some in playtest as to whether a single spell could, for example, affect any Ability or if there were different spells for different Abilities. The additional language was included in an attempt to clarify that each spell affects one Ability/Characteristic/Virtue/Flaw whatever chosen at the time of creation, unless otherwise noted.