I'm not sure what the rules are for drawing a weapon in Ars and don't think it has concepts like ready actions or mods for drawing weapons as partial actions. He probably shouldn't get his Dex or Qui in defense but it's all good.
However Diego didn't have the weapon out and I was assuming that he could draw and strike in the same action, potentially further limiting his Init.
"He's on the roof!"
Thinking Alonzo mentally "Yes, as much as you can. He's very dangerous."
And he wipes the blood into a kerchief, "Only temporarily escaped, we have a connection to him now."
(unless Roberto jumps up to the roof or his action changes this: )
"Yes, your untrustworthy friend has left you to us so drop the blade. You knew he would return in thin air, which would have been useful to us too. I give you this one chance to speak plainly and assist us, or do I need to melt that dagger to slag, and you with it?"