Hmmm.
The answers proper to this go all over the map. First, a British coat of arms is a gift from the Crown, and is inherited in an entailed fashion where only the “heir of line” is entitled to them. A second son could get an issuance of arms with a crescent as a “cadency mark” differentiating them from the eldest son who would inherit the undifferentiated arms. (According to Fox-Davies’ comprehensive reference work, the crescent marks the second son and there is nothing to indicate the points up/points down thing you mentioned.) And as jayjay notes, the crescent may not be a differentiating mark (in which case it would be “in chief,” dead center of the top of the array) but an actual “charge.”
What you describe is definitely the arms which would be displayed on a shield or coat of arms, not a crest proper, which is a single object that would appear atop a helmet (hence “crest”). The color of the fish and moon and of the background is also significant, not that you could tell that from the signet rings (but your brother might be able to run down what they’re supposed to be).
The point that I’m going for, though, is that in British law, arms are not “family” arms but specific to the heir of line of that family, the one living person who represents the eldest son’s eldest son sequence of descent most closely.
In some continental countries (I believe this is the case in Germany) arms are family in nature, but not in the U.K. In the U.S., where sovereignty rests in “we the people,” you may adopt any arms you choose without let or hindrance, excepting only that you don’t misrepresent yourself as somebody else by them. While there is a registry, it’s totally voluntary.
What Canadian law is about arms, I don’t know for sure. Matt_mcl, if he wanders through, would have the answer. But I’m making a point about British arms because most Canadians with “family arms” got them from either the U.K. or, more rarely, France, and in the U.K. it does make a legal difference whether you’re entitled to display them. Though it’s rarely prosecuted, it is a crime at law there to display arms you’re not the legal, “matriculated” heir to. And of course that may have a strong bearing on Canadian law, derived as it is from British law.
Assuming you can use these arms, or something differentiating them (e.g., put a “bordure chequy” – a two-square checkerboard pattern – around the outside of the field to differentiate them), think about having them painted on a wood plaque by a competent artist and then lacquered. I’ve seen this done and it’s very effective as a means of showing family history.