Priscilla can dodge due to her high luck, yes. But that doesn't mean her Spd ain't anywhere near that of a Swordmasters by both average and capped. She also have rather poor Support options as well other than Sain. Compare to the following potential Swordmasters:
Guy. Priscilla has more luck than Guy completely but even with those Luck, Guy still has better Speed over Priscilla where she average out 22 since Guy is able to max out 30 Spd. Let alone having +5 Atk and +25 Crit from supports factors. Especially if you were to compare them with HM bonus, it would be a joke.
Karel/Karla. Probably one of the worst units in the game. Despite that, pretty average. Combined with their speed it gives them high Evasion over Priscilla since both of them average out 26 Spd which is still enough over 22 Spd and having such low Con.
Matthew/Legault/Jaffar. Wait a minute, they're not Swordmasters? Oh wait, they can dodge like a Swordmaster because they have the exact same speed cap and average wise too.
Matthew is actually a grand example of being a Swordmaster because he higher critcal rate than Karel from support factors with xGuy and xHector. And still has better speed over Priscilla by both average and capped.
Legault applies the same as Matthew but without the support factors. But he gains a HM bonus, which turns the favors towards him. And could gain Speed very easily with that.
Jaffar is being tied with Karel and Karla but pretty low luck. Don't need to elaborate on that one.
And Lyn. She is of course a uber-Swordmaster because of her exact same caps and average than that of a Swordmaster. And she can use a Wo Dao. But Mani Katti is all the critical bonus she needs to be like one as well. Not to mention she has better speed as Guy and could easily capped it as well. And she has good support options with Rath so she could dodge much more than a Swordmaster with it.
I think I'm done. No wait. I forgot about Raven. But wait Raven's not a Swordmaster. Oh yeah, its because Raven's speed win translates into a good Evade win with supports for durability for having Priscilla's A support and Rebecca's B(If not then Wil's) Which would be capped as a Swordmaster. Especially he gains a massive HM bonus.
So yes compare to the rest of the available Swordmasters in this game. Priscilla doesn't have the speed to compete with them. Especially with Raven. And if you ask me Priscilla would want to support with Raven if he would want to get any better. And just to be clear at this she can't dodge like a Swordmaster.