Cultures do not exist in a vacuum nor are they static ...
At what point do you decide it's strength or a weakness and what makes it so?
Good question. Since you were the one who defined the adoption of "western ideals" as a strength, why don't give this question a shot?
I'd also be curious how you separate "western ideals" and colonization.
I view "western ideals" as those ideas that came out of the enlightenment - specifically in terms of individual rights, liberty, equality, democracy, a justice system where one is tried by a jury of one's peers. Separation of church and government, secular humanism. Political and religious pluralism. That is not to say it is unique to western thought, but as an entire package it is strongly identified with western thought.
I think this describes well:
Western culture is characterized by a host of artistic, philosophic, literary, and legal themes and traditions; the heritage of Celtic, Germanic, Hellenic, Jewish, Slavic, Latin, and other ethnic and linguistic groups, as well as Christianity, which played an important part in the shaping of Western civilization since at least the 4th century.
Also contributing to Western thought, in ancient times and then in the Middle Ages and the Renaissance onwards, a tradition of rationalism in various spheres of life, developed by Hellenistic philosophy, Scholasticism, humanism, the Scientific Revolution and the Enlightenment.
Values of Western culture have, throughout history, been derived from political thought, widespread employment of rational argument favouring freethought, assimilation of human rights, the need for equality, and democracy.
How do I separate it from colonization? The two are different but one influenced the other, I won't argue that.
In the Americas, it was Manifest Destiny and yes, it led to a lot of tragedy we are still atoning for.
I do think those values are a strength - but that doesn't mean they are 100% good or have not been used for bad purposes (ie - subjugation of indigenous peoples around the world).
Where I see strengths are:
The idea (not always followed in reality) that everyone in a society is equal in terms of rights. That means religious, political, ideological, ethnic pluralism and gender equality.
Governance by the people through their elected representatives regardless of religion, political affiliation, ideology, ethnic background or gender.
Separation of church from state. I know I have harped on this before in conversations. I have never seen a state who's government and legal system is largely controlled religious doctrine, truly incorporate the values of tolerance, plurality and equality. At best there seems a temporary tolerance, easily upset.
The treatment of women. I'm not sure this came out of "western ideals" exactly but it came out of western countries. The entire women's movement for equality, the right to vote, the right to independently seek employment, to govern came out of Europe/America. I can't find any ancient societies that even come close to that.