Maybe I'm being a little cynical, but I hope Eggsy never blamed himself for Merlin's death too much.
Perhaps he was careless with the mine detector, perhaps the equipment was out of order. He was scared when he felt a landmine under his foot, and I suppose he had no idea that Merlin wanted to sacrifice himself. I think Eggsy would assume that Merlin has some kind of rescue plan. After all, he hadn't brought a can of freezer with him for nothing.
I just want to say that if Eggsy had known how this would end, he would never have left the mine and probably would have blown himself up.
I have a couple of similar thoughts about Harry and Lee Unwin. Harry's mistake was much more gross, but he also had much less time to come up with something. And he was the first one who rushed to hide the grenade, and probably would have died if Lee hadn't pushed him away and sacrificed himself. I think Eggsy would have done exactly what Harry did.
I once read a post in which the author asked to distinguish between the concepts of "Harry is partly responsible for Lee's death" and "Harry killed Lee." And I think that's a fair point. And probably the same applies to Eggsy.
