POE2 Sceptre percent spirit roll question

I'm new to POE and I'm confused about something and now it's making question other parts of the game. On Scepters you can get a roll for X% increased Spirit. Is this bonus only applied to the weapon itself or should it be applied to my total lump sum of Spirit? Seems to only apply to the weapon itself.

This makes me question how percent to energy shield works. Does it only increase the armor it's on or does it add to all the increased energy shield bonuses you have within your build and then apply it to your total raw energy shield?

Yes, it's a local modifier - affects item's base stats (like ES armors with increased % ES for example).

Global modifiers are usually rolled on items that don't have the specified stats on base item - defenses on non-armor items, damage on non-weapon items, rings/amulets, etc.