You said you wanted something heavy. This Jinhao rollerball pen is several times as heavy as the other suggestions. You said you wanted a ballpoint, but perhaps you don't know that rollerballs, also known as gel pens, are considered by many to be a great improvement over ballpoints.

Someone suggested a Rotring 600. That's a fine pen. Jet Pens says it weighs 23 grams. That's sort of heavy. A Faber-Castell Essentio weighs 34 grams with the cap. This Jinhao weighs 151 grams with the cap, and, I'm estimating, well over 100 grams without the cap. And it's a rollerball, not a ballpoint. And it's definitely on the thick side. I love mine. I didn't really care for the crazy styling at first, but it's growing on me. $32.97 on Amazon. https://www.amazon.com/dp/B095MX61H4?