Knifeplay - Holding the knife that triggered

It has become a bit of an agreement between elle and I that while in play when I feel she is slipping into subspace I keep my questions to a minimum to avoid causing subdrop, for this reason that night I wasn't saying much at all. The night we played with a knife the room was near silent aside from her moans and gasps when I was paddling her until she reached that space in which she becomes unresponsive. I test where she is at with a few harder strikes, elicit a mild moan and know that she is floating in divine pain. In that place I knew it was time to turn to the knife.

I was feeling a little nervous about using the knife on her, not because I was worried about it becoming a trigger, but because we haven't used a knife before and I didn't want to hurt her. In play we differentiate between the delicious pain I deliver to her that makes her shiver and moan and liquefy beneath my touch - this is pain - and the hurt of going too far, doing something wrong that was not good, and all around bad pain - this is hurt. Hurt is to be avoided and so it was hurt that I was nervous about accidentally giving her. I was focused on the knife, not pushing too hard because I really just wanted to scratch, and being conscious of her slight movements that could make me slip. She was bound down pretty well and so she couldn't move much at all.

Especially in this scene, I didn't want to suddenly pull her from subspace so I wasn't verbally checking in with her. From my perspective, only a view of her back and responses sounding like those from other times in subspace, all was going well. I only took a half dozen strokes or so with the knife before moving on to other activities. I didn't know anything was wrong. After play and aftercare we talked a little and fell asleep. To be honest, I went to sleep a little disappointed that I didn't manage to give her any scratches to wear the next day as I know how much she loves wearing my mark.

It wasn't until the next morning as we got closer to it being time for us to leave that I noticed she was quickly fading and something was wrong. She told me then that the knifeplay had triggered her and my heart fell. How could I not know? During, after, the next morning I had no clue this had happened. I felt like I had failed her as much as a Domme could possibly fail the one they are to protect at all costs. I've read on Fetlife of Dommes just intuitively knowing what was happening with their sub, they had that connection, they could read every move every sound and know.

I had held a knife to my wife's back, and had absolutely no clue that she was trying with all her might to say her safeword! What I feel the worst about is that I didn't know at any point the feelings that must have been racing through her head as she was trying to stop me. In our lifestyle triggers are always a possibility, and accidents happen, we both know this, but to know she was trying to tell me and couldn't scares me and makes me feel even more the responsibility and trust she has invested in me. I sure hope with time I will become more intuitive with where she is at while playing.