On the subject of Harpe, I can cut the anti-heal time down to just like 6~8 hours, and considering he's not like Diarmuid who had Mind's Eye, Knight Tactics, and Gae Dearg to set up this whole ploy where Saber had to take off her armour and then take a really precise hit, I can't imagine it'll be game breaking unless team Red has someone like Spartacus who relies purely on healing.

The sack is one of his canon NPs, it's in his little stat block on the wiki and in the prototype materials, just not in the abilities section on the wiki for some reason. I see what you mean about flight but since he lacks ranged attacks he would only be immune to melee fighters if he decides to flee or something, so it's mostly for flyby attacks where quick fighters have a chance to catch him. I can see it being really hard to counter if our Archer decides to hand over his bow or something, but somehow I doubt that'll happen.