One Ordinary Deathclaw, Is guarranteed To make you crap yourself Upon encounter! Here are some glitches to make them a little less... um... Scary. Which is probably not possible.
1.If found in a Rockey Area, Deathclaws (Usually Blind and young ones) Will get caught on nothing, as if It was caught on a rock, making it a VERY Easy target as the Deathclaw does not have a ranged attack. Once in this state, the deathclaw will be unable to move untill K.O'ed or dead.
2.Talking Deathclaws may sometimes have actual Dialogue boxes! If you sneak up to them they will have a dialogue box saying what they said. You have only the options to say Goodbye. This crashes the game upon leaving the Dialoge box.
3.If a Deathclaw(or I think another creature) kills Chomps Lewis (New Vegas only) You will gain NCR Infamy, even though you didnt kill him.
4.In the Case of a Cazador and Deathclaw Combat sequence, the fight will never end. If you wait from affar, and come back they will still be fighting. The fight only ends if a human NPC or Player kills them, or the Game state is at (End)