What are my obligations as an MSc holder?

Some insight can be gained from considering the Oxford degree day ceremony, which is still conducted in Latin and uses fairly traditional formulae in admitting graduands to degrees. The descriptions used indicate various rights and responsibilities (all translations from here):

Candidates for the DD, DCL, DM and MCh (all higher doctorates) swear to the following:

Doctors (Masters or ladies/gentlemen), you shall swear to observe the statutes, privileges, customs and liberties of this University. Also when you shall have been admitted to the House of Congregation and to the House of Convocation you shall bear yourselves in them well and faithfully to the honour and profit of the University. And especially in those matters which concern Graces and Degrees you shall not impede the worthy or put forward the unworthy. Also at elections you shall record and nominate one only at one time and no more in each scrutiny, and nominate no one unless you know certainly or believe firmly that s/he is fit and proper.

For other higher degrees:

You shall swear to observe the statutes, privileges, customs and liberties of the University, as far as they concern you.

They are then admitted to the degree by the Vice-Chancellor, with the wording (for the DD, DCL, DM and MCh):

To the honour of Our Lord Jesus Christ, and for the profit of our Holy Mother Church, and of learning, I, by my own authority and that of the whole University, give you licence to incept [begin to teach] in the Faculty of Arts (or Faculty of Surgery, Medicine, Law or Theology) to lecture, to dispute and to do all the other things that pertain to the rank of Master (or Doctor) in the same Faculty, when those things have been completed which the Statutes require, in the name of the Lord – Father, and Son, and Holy Ghost.

(A non-Christian formula is available if graduands request).

Other higher degrees have a formula either conferring permission to incept (begin to teach) in the faculty, or just admitting them to the degree.

For the MA, graduands swear an oath "binding them to be loyal, obedient and faithful to the University and its interests, and to comport themselves circumspectly at elections to University offices" before being admitted by the Vice-Chancellor.

Finally, BA graduands are admitted with the following formula:

Ladies/gentlemen, I admit you to the degree of Bachelor of Arts: furthermore by my own authority and that of the whole University, I give you the power of lecturing, and of doing all the other things which concern the said degree.

To summarize, traditionally degrees were about membership in a Faculty of the university, and came with responsibilities to uphold the rules of the university, and participate fairly in elections. (These aren't empty words at Oxford, where they still confer 'MA status' on faculty members who do not have an Oxford MA so that they can participate in the governing bodies, and which still allows all graduates to vote on the Chancellorship and Professorship of Poetry). It may be that something similar is indicated in the University of Waterloo's ceremony or statutes, although it's also possible it's just traditional phrasing without anything formal behind it nowadays.