>>529819587
Outwardly and 90% of the time a noisy shameless otaku. The one of the first plot twists of Okeanos (the chapter he debuts) is that, although he IS shameless, he is purposefully doing that so people drop their guard and this clouds their analysis of him. Hektor points this out best: Blackbeard never ever lets go of his pistol no matter what he is doing so backstabbing and assassination isn’t daunting since he is rarely truly vulnerable.
In the manga adaptation, Turas Realta, Blackbeard and Drake are both boosted by a grail of their own each and they note his production of ghosts rivals Drake’s culverins which he uses in combat to shield him from all her firepower.
He is also the one that tips her in how to use the grail for that as the manga climax of the chapter has Drake learning that in order to control the dead as leader of the Wild Hunt in the finale
So, yeah, he is a servant that majority if the time is hinting he is holding back and can get serious. In-game that rarely ever happens.