An honourable person should have integrity. This integrity is an absolute and should not differ depending on circumstances, be it a change of culture, status or environment.
Allowing one's integrity to be compromised in one instance, opens up the possibility for it to happen again. Until a point when one no longer has any integrity left, making him/her dishonourable.
A person's honour is reflected by his/her manner, not only in his/her speech, but in every movement and action.
An action that demands no compensation, no reward and no recognition; when it is done out of kindness or virtue; and there is no preceding judgement or bias, that action is an honourable one.