Seems to be another tactic to make you pay twice for the same product. Would like some clarification from those who own both and can provide results on what to expect. I am assuming the weapon pack is superior to the weapon styles from the frostcaster due to frost effect difference.
The Frostcaster outfit styles are from the Crown Store only crafting motif, and are just standard motifs (and include all 14 pages for crafters). They are, however, craftable and can be traded. The Iceheart arms pack is an outfit style that must be applied in the outfit station like any of the other Monster Arms packs.
All Monster arms packs only have one version of each weapon (one 1H, one 2H, along with a bow, staff, and shield) as opposed to different axe/sword/mace/dagger versions, but the monster packs do come with particle and/or glow effects.
I always use the Iceheart styles in my winter outfits. They are absolutely gorgeous. The Frostcaster weapons are pretty boring, to be honest, especialyl compared to the Iceheart
the main difference between the opal and non-opal versions of monster weapons, is that the opal versions cannot be dyed, while you can apply dyes to the non-opal version
i actually dont like the coloring on most of the opal monster weapons lol
i have my main house (grand topal hideaway) listed in the housing tours, it has multiple target dummies, scribing altar, and grandmaster stations (in progress being filled out), as well as almost every antiquity furnishing on display to preview them