Lumbers inflict strong status as far as I know. You can't be immune to strong statuses, but you can get enough resistance to be able to get away from them. Though you shouldn't get hit in the first place, accidents happen. I think that +4 freeze resistance is enough to let you escape if you got hit reducing the time you're frozen for long enough to outspeed the silversap before it begins attacking again. I use black kat set all the time which means I have +7 resistance (still need whiskers for raiment) but I usually use shadow cloak just in case something else decides to hit me while I'm frozen. One more tip is that you face the monster you're attacking at all times so when you get frozen you'll be facing the lumber and that gives you a chance to hit back with a charge or some normal hits, with enough skill at single switching and the right weapons you can kill it while you're frozen in less time that it requires to charge its arm at you again. Keep in mind that you can always use remedy capsules or pet abilities to get away.

I never knew that, thanks Zeddy. (off-topic) Also I've been wondering why are you never online? I'm Geo-Senpai in case you don't know.