Calculate grades based on pass/fail percentage
The function's parameters are implicitly passed by reference, which probably isn't the intent since none of the parameters are assigned/returned to the caller.

Signature should pass its parameters by value, like this:

Public Function Grade(ByVal Points As Integer, ByVal MaxByVal As Integer, ByVal Cesuur As Double) As Double


maxGrade and minGrade are only ever assigned once - they're essentially constants and could be declared as such:

Const MAXGRADE As Integer = 10
Const MINGRADE As Integer = 1


I would suggest to declare variables closer to their usage, and perhaps only assign the function's return value in one place.

Variables restPoints and restPass are only ever used with a passing grade, in that Else block. VBA doesn't scope variables at anything tighter than procedure scope, so you could extract a method to calculate a passing grade, but that's borderline overkill - here's what it would look like, with parameter casing to camelCase:

Option Explicit
Private Const MAXGRADE As Integer = 10
Private Const MINGRADE As Integer = 1

Public Function Grade(ByVal points As Integer, ByVal maxPoints As Integer, ByVal cesuur As Double) As Double

    Dim passPoints As Integer
    passPoints = cesuur * maxPoints

    Dim passGrade As Double
    passGrade = (MAXGRADE + MINGRADE) / 2

    Dim base As Double
    base = MAXGRADE - passGrade

    Dim result As Double

    If points &lt; passPoints Then
        result = 1 + (passGrade - MINGRADE) * points / passPoints
    Else
        result = CalculatePassingGrade(MAXGRADE, base, points, maxPoints, cesuur)
    End If

    Grade = Round(result, 1)

End Function

Private Function CalculatePassingGrade(ByVal base As Double, ByVal points As Integer, ByVal maxPoints As Integer, ByVal cesuur As Double) As Double

    Dim restPoints As Integer
    restPoints = maxPoints - points

    Dim restPass As Double
    restPass = mxPoints * (1 - cesuur)

    CalculatePassingGrade = MAXGRADE - restPoints * base / restPass

End Function