Sounds like the healer was an idiot.
I've tanked Nexus in less than what you're wearing. Actually, way less considering I was wearing nothing and only wielding my axe. A healer told me I was undergeared for Nexus, so I had to show him what undergeared for Nexus was.
It's the small things in life that makes it so much fun.
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Please "talk up" if your comprehension white-shifts. I will use simple-happy language-words to help you understand.