Yes, that's exactly why combat worked the way it did. The beholder couldn't see you until you hit it, but once you hit it, it starts moving eratically. And because it's such a fast bugger, it was hard to catch up with him. When you equipped the torch while you were locked in place, it could see you and immediately started attacking you.
I forgot to deactivate the bridge trap :') you'd have to go all the way up again, but there are a few shortcuts (like the ladder near the shop) that can skip some sections. It would still be frustrating, but it shouldn't take long to get back up without enemies etc