Well i didn't get it during the trip anywhere else i can get it?
There is only one Iron Frame, and one place to get it.
You don't need
it to beat the boss. In fact, it gives a very, very, small advantage.
If you are a completionist, read on for SPOILER:
Your only opportunity to get the Iron Frame is when you go to Loredo's compound for "Indecent Proposal." Roche will tell you to sneak around back to check things out. It is possible to fulfill that part of the quest without finding the Iron Frame. If you climb up to the window and listen to the conversation between Philipa and Loredo, you will be told to head back to Roche. When you are safely back to him, the quest moves on.
If you want to get the Iron Frame, you need to make your way into a walled-off storage area. This area is in the direction of the front courtyard, but accessed from where you sneaked into. You can scale a wall or go through a door to get into it. There are many chests, bags and crates. One of the chests has the Iron Frame. You can easily get back to the main courtyard from this storage area.
Regarding the Kayran fight and the Trap SPOILER:
There will be a glowing symbol on the ground to interact with via left-mouse, if you have the Kayran trap. Once you deploy it, it will be difficult to see it, but it is there. The beast may not drop a tentacle in it right away. Seems to help if you stand near the trap and roll away. (This is when you may notice it is hard to see that trap in the grass.)
Anyhow, using the trap saves you slicing one tentacle. Doesn't save you the trapping part, since you have to do that with Yrden any way. So, it buys you 5 seconds. No big gain.