He was aware that garrosh would have

He was aware that garrosh would have to be killed, but WOW Classic Burning Crusade Gold only as an option last resort. It's true that he could've done in the direction of a warrior and cut off his head, or cleave him using an axe or brutally punch him or smash his head using the doom hammer but the thought of that was too cruel. The final choice was the electric chair option of execution through a single quick hit of lightning. I'm assuming death was fairly painless for garrosh. He is struck by lightning and is unable to sense.

What I'm trying tell you is that the warrior within thrall didn't have the ability to kill him. It would have been an even more painful and brutal death for garrosh. Honor is the responsibility of the warrior. The wild one is shaman. The elements are wilder and more uncontrolled. They are able to be pushed and pulled at, and they can destroy the person in an instant.

Also, it is possible that thrall lost his warrior-like skills because he hasn't practiced enough. He mostly utilizes his shaman talents after the end of the war, using archimonde. Perhaps thrall is weaker as a fighter at this point. Now that he's holding dragora his strength is greater and could possibly kill the makgora day garrosh with an axe toss "for Azeroth!" Like it was the case with Helya!

Although Thrall killed Garrosh through his shamanistic capabilities however, he was still feeling guilty about how he dealt with the incident and how Garrosh ended up being the result of Thrall's actions as well as all the other circumstances that led to his losing his power.

Are we really unable to summon earth bridges? He summons earth bridges in legion as well as in the sanctum de domination. It's more likely to be due to him refusing to use the power he used in order to take out garrosh.

But he's not feeling guilty. When talking to drake He mentions this to her in korthia. She assures him that it's not his fault.

In the internal debate, Thrall splits between guilt and the fact that it was his fault. He said that garrosh was at fault when he killed garrosh. But he was torn that he had led garrosh down the same path that led to those choices. I do believe we will have thrall returning to his shamanistic self after the discussion with Drake in korthia.

Following Assault on the Broken Shore Thrall says to the Shaman adventurer that from the moment he killed Garrosh it was like Doomhammer was simply a weight that is not in his arms and that Elements abandoned him.This is the message that book Words of Wind and Earth(the book that teaches you about buy WOW TBC Gold Shaman artifacts) says: