TORONTO, Dec 14 (Reuters) - Canadian financial dealmakers are raising the alarm about Ottawa's proposal to more closely scrutinize national security implications of foreign acquisitions of Canadian companies, warning that such interventions could deter foreign investments and slow impending deals in critical sectors. Last week, Canada announced its biggest overhaul in more than a decade to Investment Canada Act, allowing the government to impose interim conditions to prevent buyers from accessing trade secrets, and to block investments that could compromise national security. Lawyers and industry associations say such conditions could delay and add to the cost of dealmaking. "There is...