Just making a note of what art modifiers were changed from the X360 version to the PC.

Weapon X360 PC
Longsword (Emma Custom) Power Speed
Longsword Power Speed
Superior Longsword Power Speed
Superlative Longsword Power Speed
Might Longsword Power Speed
Runic Longsword Power Speed
Might Tuck Power Speed
Runic Tuck Power Speed
Celapaleian? Power Speed

That should be it... Will do another few sweeps of both JP guides in case I missed something. The Famitsu guide has the DLC only equips, but the entire equipment section is sorted only by the 50 sounds. Not being filtered by WT makes scanning for info much harder and slower than it needs to be.

It seems that the Longsword line was changed over to Speed to help Emma/Emmy add the Speed modifier to their arts, instead of being stuck with nothing until upgrading to the Bluesteel line (or requesting the Nightbloom in Emmy's case). The Might/Runic Tuck might be in the same boat for Emmy when she's Combat/Mystic focused, most likely stopping her from adding the Speed modifier until she finally finishes upgrading her offhand to the Superior Bluetseel. She doesn't upgrade to either of those Tucks on the PC (can still get her to request them), but it's interesting to note.

Not a clue about the Celapaleian, but that's because I don't remember who would request such a low rank Spear, or who upgrades to it. The S-E guide lists Power, Famitsu has Speed.

(I had Crimson Dagger there before, but that's because I had misread クリス・ナーガ's entry, which was right above. It mods for Speed in both versions.)