How did the exams go? I’m going to guess that since you’re still in track for a magna cum laude, that went well (sure hope it did). 
Just a disclaimer, I’m not a specialist and have no experience in the ecomonic fields, nor with academic job pursuits, so take everything I write with a grain of salt. Also, this is going to be a wall of text and I don’t know how much of it, if any, will be actionable, so feel free to stop reading whenever you want.
Focus on the future: where are you going? How are you achieving that? What in your personality and/or past experience give you that ability? If you can identify what they’ll think of as a weak point and turn it around in your narrative before they ask, that’s a bonus.
I’d not talk too much about what I’ve learnt, I’d let them ask about it and be ready to answer any question. I’d rather focus on vision, what you are building. That’s a premium they won’t find in anybody else. You’ll probably “have” to explain the switch from philosophy to economics, that’s easily done by telling them of your drive, what brought you there (in economics) while embedding the why of your philosophical degree and what it brings you that others don’t have into it. Bonus points if it’s geared toward a soft skill useful in their business/research (social ethics, personal ethics (you can mention some of your favorite thinkers, my own drive would have been in Marc Aurelius’ stoicism and a mix of Rousseau and Ben Franklin)).
2 cents example: “I’m an observant person, growing up, I would watch the people around me and wonder what made us act the way we do. What drives us, as human beings and as a society? Why do we get out of the bed in the morning and act the way we do? Philosophy brought me that, but as you can guess, while philosophizing brings great life and global thinking abilities, it’s a hard trade to make a living of. That’s why I have pursued my other passion and am now postulating to join your team.”
Much like market timing, you craft it in hindsight but tell it as if you had aimed for it while doing it. What are the data points in your life? How can you link them together to make it attractive while still aligning with what they’ll discover of you working with you (you don’t want to craft an illusion that’d be dispelled later on, while you are definitely putting lipstick on your life, you want your life to still be recognizable under that)? Be sincere, but show drive. Focus it on things your prospective employer is seeking (clues that you’re in for the long run, social skills, craftiness, ability to stay professional in the face of difficulties, etc.).
I’m a geoscientist who’s turned toward engineering. There’s not a single diploma that I’ve done in the regular time (make it a year longer whenever I’m involved) yet, my CV has things like political experiences, social groups and organizations leadership and a couple of names of people on whom I’ve made a good impression with their number so they can be called if they have question on my work ethics and personality (make sure the people you cite are ok with that. Right now, it can be some of your professors. Later on, it’ll probably be work relations). It’s not about the people themselves and what they can say, it’s about displaying that you’ve made a good enough impression that people would stand up for you, and that you’ve not afraid to have them say whatever they would about you. When I speak about my experiences, engineering and shaping my environment is my drive. That requires knowledge of said environment, which is fulfilled by being curious and dabbling in many things. That knowledge allows me to find solutions outside my field to apply lateral knowledge to the problems I am facing, understanding people’s needs and knowing how to address them to get their help on my own projects. Much like water (I’ve worked in hydraulics), I find my way and don’t let obstacles stop me.
The focus point is being honest, finding your drive and telling them about it. Passionate people exude an energy that is hard to resist, even when you’re a serious professor/business person in a suit and tie. Find what makes you passionate when you talk to your friends, sharing a beer, and tell that story.
I’d ask myself if I want to work in an academic position (keep on with the research assistant positions) or in the industry (internships add real value, both in terms of experience and networking. In my view, that’s worth making your master thesis 3 months longer if it comes to that). In my experience, 50% jobs are very hard to find (I’ve spent my Master searching for one to do beside my studies). 80% might be more feasible.
Oh yeah, Coronavirus. I had (serioulsy) forgotten. Yep, you gotta adapt and make do with what you have. Kuddos for doing it.
I’m with @dbu’s excellent advice. Find something you’d be interested to do, do it, show it. Anything related to tracking your favorite stocks/indexes, expenses or strategies would do. Also, if you can make use of it during your master thesis, that’s a bonus: there are deadlines and quality expectations on it so it should give you extra motivation to get at it even when you’re tired and think you’ve done enough.
Also, unless it’s a very specific paper (make that a MIT diploma), in my opinion, papers are useless and I wouldn’t want to work for someone who puts real faith in them. That’s just me, though. I’ve spoken with a HR specialist that told me doing a Goethe B2 would look good on my CV so some people put value in it (I’m sticking to my view both that B2 level in a language isn’t enough to make it really useful and that displaying the skill is worth a whole wagon more than having a paper saying you have it).
You seem to be doing really well and your drive is tangible, I’m not worried you’ll find your way and convince the people around you that you’re a good fit for whatever they want to do. It won’t always be easy and you may have to stumble a few times to finally break through (or it might work on the first try) but I’m sure you’ll rock whatever you set your mind to.
) could be to try and reproduce the visualization from this post: Coronavirus: when do we reach the bottom of the dip?.
