The Skeleton and ghost can equip all armor except Hoods and Padded Helmet. They can use from the list of weapons below.

SkeletonAxeIron
SkeletonSLedgeIron
SkeletonSledgeJump
SkeletonSwordBronze
SkeletonSwordBronzeKick
SkeletonSwordBronzeSmite
SkeletonSwordBronzeTaunt
SkeletonSwordIron
SkeletonSwordIronKick
SkeletonSwordIronSmite
SkeletonSwordIronTaunt
SkeletonSwordSilver
SkeletonSwordSilverKick
SkeletonSwordSilverSmite
SkeletonSwordSilverTaunt
SkeletonSwordSilverPoison
SkeletonSwordSilverPoisonKick
SkeletonSwordSilverPoisonSmite
SkeletonSwordSilverPoisonTaunt
SkeletonSwordBlackMetal
SkeletonSwordBlackMetalKick
SkeletonSwordBlackMetalSmite
SkeletonSwordBlackMetalTaunt


For the weapons SkeletonAxeIron, SkeletonSwordBronze, SkeletonSwordIron, SkeletonSwordSilver, SkeletonSwordSilverPoison, SkeletonSwordBlackMetal
in order for these to function, they must be set with a specific animation for example SkeletonSwordBronze@swing_longsword0 or SkeletonSwordBronze@jump_attack

if you want your skeleton to do multiple animations with the same weapon type you could give him all weapons
SkeletonSwordBronze@swing_longsword0
SkeletonSwordBronze@swing_longsword1
SkeletonSwordBronze@swing_longsword2