The European sovereign debt crisis of 2011-2012 revealed the currency union's fragility, which essentially emanates from the tension between a single monetary policy and decentralized fiscal policies. While considerable efforts have since been made to strengthen the Economic and Monetary Union, the COVID-19 pandemic has once again laid bare its weaknesses. To cushion economic and financial shocks and sever the sovereign-bank doom loop, several policy proposals to create a common public debt security have been put forward. However, none of them has so far seen the light of day. This paper reviews the following most promising asset proposals from a legal perspective: (a) sovereign bond-backed securities (SBBS), (b) E-bonds, (c) Purple bonds and (d) Coronabonds. While SBBS and E-bonds are synthetic securities, employing means of securitization to reduce risk-sharing, Purple bonds and Coronabonds involve at least a partial debt mutualization across the Union. Rather than focusing on the feasibility of these proposals under EU law or national constitutional law, this paper adopts the investor's perspective and reviews the safety features of the respective proposals. Specifically, it compares the proposals against the backdrop of the following formal and functional legal characteristics: (i) governing law, (ii) dispute settlement forum, (iii) investor protection, and (iv) investor representation in sovereign debt restructurings. As is the case with any other public debt instruments, these elements are vital for the assessment of legal risks associated with the investment. They thus bear direct relevance for the feasibility of the asset proposals, the pricing of these instruments by private markets, as well as their suitability to achieve the objectives envisaged by economic policymakers. I conclude that while much progress has been made in identifying and calibrating financially and economically sounds assets, critical legal questions have not yet been answered to a satisfying degree. The paper thus recommends that policymakers provide more clarity on the legal basis as well as crucial legal design features of the respective asset with a specific emphasis on those legal characteristics that render assets safe for investors.