That's Baku's guide. I was in the process of writing a new one but I sort of got bored before I even started the important stuff.
Swords are better. The damage gap is actually not apparent enough in normal play for it to matter to most people. Swords are safer, faster, and it takes 3-6 Butterflies from Hammers before they can out-DPS an Amaranth spamming Sword. Hammer only shines if you can pop Slashing High and spin2win, which requires a good bit of Def on most raids. The only other benefit of a Hammer is the +1k Att you'll get from weapon stats.
Quick name reference.
Swords
R - Rose Thorn
LRR - Petal Toss
LLRRR - Blossom Blow
LLLRRR - Ivy Sweep
LLLLR - Amaranth Kick
Hammer
R - Honeybee Sting
LRR - Crushing Arc
LLR - I honestly should know this but I sort of forgot
LLLR[R] - Butterfly Swing
LLLLR - Stigma Hammer
And now the more important stuff. Sorry Q, but I'm going to brutally criticize your post.
Eh I was in the same boat, and decided to just google around for quiet a bit. From what I gathered + some playing experience now, your main mob killing moves are going to be jump smash and LLR, or an occasional LLLLR or LLLR. Your LLLR move is Butterfly Swing? Where you just pretty much spin to win with hammers lol. Best combo is to combine this with slashing high. Coupled with OP fiona defense = Tanking + damage + no knockback. Kills hidden boss fast for easy exp until raids.
I don't jump smash ever, it's mainly out of habit though. Jump smashes have very weird hitboxes, and unless you're one shotting with jump smash, it's not worth it.
For swords, Petal Toss 2 hit (requires r9) is my main mob clearer. Blossom Blow isn't very good as it has a relatively small hitbox, while 2 hit Petal Toss has the damage and the range to cover as a mob clearer. Your other moves are Ivy Sweep and Amaranth. They both do about the same damage, but Amaranth is faster and is more stamina efficient, so it generally takes priority. Ivy Sweep does have a better hitbox to your sides, so use that if you're somewhat surrounded.
For hammers, Crushing Arc 2 hit (requires r9) is still your main mob clearer, and it's essentially a slower Petal Toss with a bit more damage. LLR is useless on Hammers, please don't ever use it. Butterfly is generally your best mob clearer, it's a huge stamina hog though. Stigma is better than a single Butterfly, but most of the time charging it is absolutely useless unless you don't have the stamina for 2+ Butterflies.
Fiona's defense is hardly OP nowadays as well. Do not be one of those Fionas who HS everything, Ep10 will kill you and kill you and kill you. Your Def is only 1k-2k above everyone else's due to your shield, and that won't save you if you're only sitting at 5k-6k without shield. SH is not going to take advantage of your blocking, if you block during SH you're not exactly being efficient.
Rank your armor masteries for whatever armor you want to wear once you hit 60. Same goes with your weapon masteries.
Max Crit hit, combat mastery, smash mastery, and defense mastery.
Crit and Combat Mastery are both optional on Fiona. In fact, it's still better to whiff your normal attacks sometimes, so sometimes you're not even getting normal attack damage. Criticals are nice, but not crucial on Fiona. You're wasting AP if this is one of your priorities. Smash/Def are fine.
Also just use Plate, the only time you won't use Plate on a Fiona is if you're confident and are running a low Def set and completely relying on your blocking/dodging to get you through. If you're doing that, you don't need my help.
Counterattack is supposedly another must max, and insanely OP too. Only problem is that it's kinda hard to use imo. Or well, it takes some getting used to playing a fiona and spam blocking fast enough to be able to block and counter attack.
Not as urgent if you're using a leap character. You will NEVER counterattack on a raid boss once you get past Klaus. Given they reduced the shield durability usage of CA and added a double CA, you should be able to get by with a relatively low rank.
I'll write some more later, but I just want to stop any random ideas you guys have.