So from what i know if you gained trait through something like Nor am i a Stranger and then got Herugrim on yourself, then if you lose former attachment you can still keep Herugrim.

But what if you got a Gondorian Shield and then got Steward of Gondor later? Do shield becomes +2 def?

P.S. Also, Dimrill Stair means just discard, not put out of play, right? It says discard from play, so little confusing.

Yes-- if you put Gondorian Shield on a hero who is not Gondor, and then later give that character the Gondor trait via Steward of Gondor, the shield will become +2 defense.

I'll leave Dimrill Stair to someone else-- just ran out of time to look up cards!

Yes, Dimrill Stair just discards Freezing Cold. When things are "set aside, out of play" during setup, that means those things are not in the game at all, but technically cards in the discard pile are also not in play, thus "discard from play" does actually make sense.

Nice! Thanks!

So i was playing with Legolas and got another question

Does activating Legolas ability prevent me from using response of Foe-hammer (because i am missing the timing now)? And vice versa?

No, you can trigger both. You trigger a response off killing the enemy, you are still at the point of having just killed that enemy and can trigger other responses. If your Foe-hammer draws you another Foe-hammer you can even play that (if you have another weapon to exhaust). The opportunity for such responses hasn't passed until you do something else. So for instance if you used Beravor to draw cards in the hope of getting another Foe-hammer, then the opportunity for responses would have passed and you wouldn't be able to play it. But you can use multiple responses off the same trigger.

That is a very good news