It's kind of sad how pointless her F-Tilt feels. Like anything it does is outclassed by D-Tilt or U-Tilt. Doesn't even catch rolls for some reason, it's silly when people just roll into it and punish you. Slow, weak, super punishable... Personally, I think all it needs is to be safer on shield, make it harder to punish when spaced well. Basically, let her cancel out of it much earlier, so it can become a good footsies tool, it already has slow startup and it lasts long enough to be easily punished if it's dodged.
While giving it a longer-lasting hitbox matching the appearance would be nice, I don't think it will do much other than just give her another very situational niche of easier roll-punishes, which her other tilts can already do. Damage would help a lot, maybe, but it's inherently more of a zoning and poke tool, so it'd be weird to make it become a source of damage.
But let's be real... we can't hope for much after Palutena has only gotten a few laughable changes since the game's been out, not to mention totally ignored lately. I'd rather discuss what F-Tilt can do, because that's all we have for now, and as far as the foreseeable future. Besides, even F-Tilt has some alright uses, and Palutena is a very unconventional character, I think squeezing in niche use of 'useless' moves is what can really make her gimmicky moveset shine.