warthogs (my pet of choice) do NOT do blunt damage.
the following is a quote from the exhaustive research done on pets found in this link
http://www.guildwarsguru.com/forum/s...ad.php?t=89491
(4) To test the damage types of the pets we needed to find creatures that responded differently to the various damage types. The Skeleton Rangers outside Bergen Hot Springs were brought to my attention by Daegul Mistweaver, as he had noted that they were vulnerable to blunt damage and resistant to piercing damage. These resistances were confirmed and data was recorded vs. these foes. The skeletons (after some testing) were shown to have an AL of 56, +20 vs. piercing, -20 vs. blunt. All animals tested showed the same damage (t-tests failed to reject differences of means between them) excepting the Dune Lizard and the Black Widow, both of which scored ~30% lower damage. This suggested that either all animals do blunt with the Spider and Lizard dealing slashing, or that all animals dealt slashing excepting the Spider and Lizard, which deal piercing. The exact types were confirmed via use of Greater Conflagration; this did not change the damage dealt by most animals, but increased the damage from the Spider and Dune Lizard to the same range as the other animals. Each pet was at level 20 with 12 Beastmastery; a total of ~2300 attacks were recorded against the skeletons, providing a very clear picture of the damage ranges and distributions should anyone wish them.