Luckily, I told Arachne was just staying at the safe house and relaxing, because I'm loooooost! 
For what it's worth, she could restore Roberto back to visible easily. He knows that...
And then, I read this 
When Roberto arrives to the safe house, he finds Arachne quietly spinning a another net. Hearing his voice, she raises her head.
Roberto? Is that you? Please, don't scry on me invisibly, it's bad form^^ Now, what have you done?
...
Are you all right?
Once things are cleared up, since his Parma is down, she can Unravel his Veil of Invisibility easily, despite the dominion:
9 + 51 - 9 (Aura) - 20 (spell level) = 31.
When she sees the flambeau's wounds, her expression changes slightly, from light teasing to concern, but then, she recovers.
Urk. That gotta hurt. Let me see, you rushed in again, didn't you? And now, I gotta pick up the pieces.
She sighs, looking at her beads
These take time to craft, you know? So be careful, next time, try to avoid getting hurt. Now, be a good boy, and lower your parma an instant
She presses one of the beads to Roberto, mumbling a command word while doing to.
Instantly, Roberto feels the pain from his wounds disappear, his aches vanishing under a comfortable soothing (effect similar to Endurance of the Berserker, sun duration)
There, this should keep you running for a little while. So. Tell me about it. What happened?
(Since it's easier for me to record, I scrapped one full bead from her reserve. If need be in this story, she can do that once more without it changing my account)
(BTW, thanks Marko, for remembering Arachne. Not only were you right on cue, I had fun writing her reaction to Roberto's wounds as a mix of old soldier and granny.
Not that much.
First, this means you need to cast 2 spells to disable your opponent, whereas he possibly only needs one.
Then, it needs to penetrate, and the higher his parma, the higher the spell you need (and thus the lower your penetration). If you try to fast cast, that -10 to penetration may be a game changer.
Last, if a combat magus really fears it, he only needs to learn a low-level version, and master it for Magic Resistance to render the spell useless against him*.
In regard to all these, an assassin with a Call to Slumber is often far deadlier: He only needs one spell, and it's only level 10.
Arachne is faaaar better at this than Roberto, but even her would think twice before engaging a dedicated Flambeau in direct combat even slightly younger than her, especially if he's got a focus.
tl; dr: Don't worry about it 
- The things that, IMO, make old magi different: Not so much extreme arts (these tend to cap of after a point), but number of spells, masteries, and custom spells.