Autumn knight's sword drop rate?

[Dinodinodude]

I can't seem to get the Autumn knight's sword drop. Last time I played with my story character I spent a good half an hour trying to get it, and got 6 Winter's Bite spears, and the sword only dropped once but I accidentally left the room before I realized it did drop. I'm back on again and I already got 2 Winter's Bite spears, is the drop rate different or am I just unlucky?

Edit: Just got it, but I didn't realize it's worse than my current sword

I'd still like to know the drop rate, though.

 

[Jenkolegs]

I THINK it's a 0.1% (1 in 1000) drop rate as it is a super rare.

Also the increase in ASPD is worth it to me.