The crack in the wood was probably caused by the steel tang flexing just a little when you swung the heavy blade. Also possibly due to expansion and contraction of the steel due to temperature changes. I wonder if there is a big temperature differential from indoors to outdoors, given that you're in Sweden.
It looks to me that you could get some superglue into that crack. Capillary action and gravity will draw it in, and it will probably take several applications to fill the crack. When done, sand off any excess. The crack will be barely noticeable.
Since this is not going to be a "user" due to the weight, and since it is full-tang, you don't have to worry about weakness in the handle. I doubt that even the short piece on the end will ever come off.
I've also had a problem with the weight of this model. The Falcatas are beautiful, but I would need a two-handed grip for anything 3 lbs or higher. I'd like to see lighter weight Falcatas, or a model with the Falcata type blade and guard but a handle shape that supports a two-handed grip. Maybe a longer, slightly down-curved handle with a downswept end that doesn't get in the way of a two-handed grip. I suppose it wouldn't be a Falcata without the umbrella handle, but it would be a great blade.
I believe Shavru mentioned that original Falcatas that have been dug up weighed around 36 ounces. HI Falcata are noticeably heavier, as most people who buy from HI buy with wood processing or brush clearing in mind and not martial arts or combat. I personally would love to see HI Falcatas that have a weight closer to that of historical Falcatas.
I keep a V-42 Stiletto by my bed. I keep it there because I know that no matter how I grip it when I grab it off the nightstand I will be holding it correctly enough. My Thamar Yek Chirra is close by as well, just not where I will grab it instantly the moment I wake up.