Loki seriously is like Luffy. Harald's practically giving Loki the opportunity of a lifetime to not only ascend the throne but to become known as a hero. But considering the circumstances in the present (most giants hate/fear Loki, and still admire Harald), I'm guessing that Loki refused and willing chose to be known as the one who killed Harald to steal the devil fruit; just so Harald's legacy would remain clean to Elbaph, but also that Elbaph doesn't fall back to it's past of violence, all for the sake of the dream shared by Harald and Ida.
If you ask me, having Imu's control-tattoo on Shanks's left arm cheapens Shanks sacrificing it to save Luffy (all the way back in chapter 1).
"He gave up a limb to save a kid!?"
--> "Actually, no. He wanted to get rid of it anyway; saving Luffy was just a bit of a bonus."
I suppose it depends on how you see it. But honestly, Shanks sacrificing his arm to save Luffy, never made much sense to me (well once we started having an understanding on Haki) considering how powerful Shanks is. In fact even the idea of Shanks sacrificing his arm to get rid of Imu's mark doesn't make sense when it becomes a question as to why not just get rid of his arm sooner. He doesn't need a Sea King to do so. Shanks could just cut off his arm or have his crew do it for him.
However if you look at it from a different angle, things actually make sense. So rather than "Why did he give up his arm then?" or "He always wanted to get rid of it", it's more about "
What did Shanks losing his arm mean to Luffy?":
When you look at it from that angle, then it doesn't matter why Shanks didn't choose to remove his arm sooner or whether it was to save Luffy or just remove Imu's influence. The lost of Shank's arm served a major point for the series and that remains unchanged even now, which was a message and seed of inspiration for Luffy about the type of Pirate he'd want to be. This combine with Shank's words to Whitebeard, about giving his arm up for a new era further implies that what Shanks intentions at that moment wasn't about just saving Luffy, or ridding himself of Imu's influence. But more importantly it was to help give Luffy the push he'd need. So Shanks had to lose his arm at that moment and in that situation
This of course is based on the idea that Shanks knew exactly what the gomu gomu no mi really was, and that he was looking for the most suitable candidate for it. Luffy eating it threw a small wrench in Shanks plans, but managed to not only salvage the situation but even improve it.
That's at least how I see his sacrifice.