Both the Enchant Weapon skill tree, and the Static skill tree, make reference to a subskill called “Zap.” However, unlike other cases where the same subskill is referenced by multiple parent skill trees (e.g., Bone Armor in Acolyte), these are not actually the same skill, and the nodes on the two trees do not apply to one another’s versions of the “Zap” skill.
In fact, it appears that the version on Static tree isn’t even really called “Zap” - the tooltip is simply wrong. The subskill triggered by the Static skill tree is actually called “Lightning” and has different effects (e.g., true Zap has 250% added damage effectiveness, but Lightning has only 100%).
You can see this by mousing over the nodes that modify the subskills (not the nodes that give you the subskills) and holding [alt]:
Actual Zap skill:
Lightning skill:
You can also see that these are two different skills on LETools, which has database entries for both of them: Zap, Lightning.
The tooltips (probably the ones in the Static tree, specifically) should be updated to more clearly indicate that these are two totally separate subskills, rather than introducing confusion by referring to both of them as “Zap”.