This whole Story of Xebec & Harald reminds me of Tiger & Otohime,
Both wanted better Life for their People, but They picked Different Paths to it,
Otohime who wanted to Ally with Humans, ended up Killed by her own People,
While Tiger who wanted to Fight Humans, ended up Killed by them, (After Helping them)
Xebec (Our Tiger here) was probably Killed by WG, after Helping an Innocent Member of them (Maybe He exchanged Shamrock for Teach),
Harald was Killed by his own People (WG had Nothing to do with it), also just like Hody, his Killer is One who Stole Country's National Treasure, Not only that, but Hody to Successfully pull both of these, He worked as a Royal Guard,
So the way I look at it:
1. This Giant worked Close to Harald
2. This Giant grew up in the Old Ways of Elbaph
3. This Giant strongly hates seeing Giants not Dying in Battle
4. This Giant is Respected enough so that He can fool the entire Country + Harald's Royal Army
5. This Giant made sure to make himself look like He have an Alibi
6. This Giant is the One who made Everyone believe it was Loki who did it
7. This Giant can be Weak, but He relies on DF He stole to become Super Powerful (Similar to Hody & Steroids)
8. This Giant is an Enemy of WG/Imu
One Character matches all of this & that's Jarul!
He simply doesn't feel Right, especially with that Sword in his Head, it's like Oda's way of telling us this is The Villain,
I mean if Jarul somehow returns to Prime (Becomes as Strong as Dorry or Brogy) & then you give him Elbaph's Legendary DF, We could be seeing a totally Unexpected Super Villain,
Imu wanting Jarul Dead wasn't Random, that guy is Extremely Suspicious,
I think He is Hody of Elbaph & seeing how Old He is, I think He knew Davy Jones or Oars or something similar to how Hody looked up to Arlong, I mean when you think about it, since He is Generation of Pirates before Dorry/Brogy, Oda could have made him +200 or +250 Years or at least +300 Years, but +400?? He definitely have some Old Agenda