Tycoon is a shady company that is simply trying to get people to buy an addon that is a 'lite' version of a free addon that is actually better (TSM). The company behind it buys dislikes on YouTube videos from other 'gold-makers', refuses to offer support if, for example, your computer crashes and you lose your addon (you'll have to buy it again), and pays random people to praise Tycoon on YouTube with no personal use of it at all. Overall, just stay clear of Tycoon and any of its affiliates.
Heirlooms are special pieces of armor that level up with your character, so they have stats that are always respectable for your character’s level (up to level 110). Heirlooms that fit the head, shoulder, chest, legs, and back armor slot offer an experience bonus. The total bonus is 45 percent if you have them all. It’s also possible to acquire a ring that adds another 5 percent, but you must win a fishing contest acquire it, and that can take some time.
I think this may have been a case of that specific sword simply having wildly inflated secondaries. If I recall correctly, when I played during Wrath, +STR and +Hit were the stat kings for plate DPS classes (I remember all the guides recommending +STR gems in every slot and +STR enchants on everything) and secondary stats were, well, secondary, and inflated secondaries on a weapon weren't that big a deal. But now that secondary stats have so much more importance, I suspect that an "outlier" weapon like that just wreaks havoc with modern calculations, so that all the addon sees is that this particular sword offers +15 more Haste and Crit than everything else that drops.