Here is what I'll probably do:
Pickpocket DC20 for the rogue to snatch a readied weapon from a sheath. It's meant to be pulled out quick and easy without fuss so that's why I have the DC that low.
DC15 reflex save for the fighter to figure out what's happening and "move" it out of the way. Step to the side, swing his hips, whatever you have.
That gives both the rogue and the fighter a decent chance of winning. DC20 is still pretty rough on a low-level rogue and DC15 reflex isn't THAT bad for a fighter by the time a Rogue can do a DC20 reliably. Fair to both parties IMHO and makes pickpocket a bit more useful as a skill for a PC rogue to have as well.