You should do one of two things. Either (1) fire your lawyer and obtain competent counsel, or (2) demand that he pay for the "second opinion" (in actuality, co-counsel or a consultant) if he is unfit to offer a proper opinion on the case. I am unfamiliar with the bar rules in Canada, however I am willing to bet they require one be competent to the prosecute the case they take. In the U.S. in all jurisdictions, the bar rules demand that an attorney not take a case unless he is competent to prosecute it. If he is not, he has a duty to either decline the case, or to find competent assistance to bring the case to closure. Unless your lawyer told you at the outset that he can only represent your defense and not your counterclaim, then he needs to be able to advise you about both issues. You should not be responsible for obtaining a second opinion. Most lawyers would not want their client seeking a second opinion as it reflects poorly on their ability competently practice. The fact that this guy has the gall to ask you to get one is unacceptable.
As an example: I recently had a case that was within my practice area. During discovery I realized there was a substantial ERISA issue. This is a very specialized area of law that I am not very adept at dealing with as it is a complex regulatory scheme I don't deal with regularly. So...once I spotted this, I contacted an colleague who specializes in ERISA, who told me what I needed to argue, and gave me a primer on the area of ERISA law that I needed to be adept at. If I didn't have a friend who worked in this area, I would've had to get a co-counsel (at my own expense) by either splitting my fee, or by hiring him as a consultant but being personally responsible for the cost. If I didn't think that would be cost effective (i.e., the value of the case was not big enough to justify me hiring a consultant) then I would've had to tell the client that an issue arose that I was not competent to deal with and that he needed someone who specialized in that area (the problem is that people who do ERISA law aren't litigators traditionally) and had the ability to litigate. Or, give him the opportunity to say, "No, I want you to be trial counsel and we will hire him as the ERISA guy." In that case, the client would be responsible for the cost of the second attorney (otherwise I would just withdraw), but I couldn't demand this. What your lawyer is doing is trying to get you to ensure he does't get it wrong, and that is not OK.