Spearmen get Hyper Body, which boosts your max HP/MP(MapleStory gold) and that of your party by 60% when maxed. This skill is particularly useful for helping partied Thieves, Archers, and Mages to survive more hits from enemies and/or PQ bosses. They also get Iron Will which gives +20 wep def and +20 mag def for 300 sec. It is basically a nerfed Bless with 100 seconds more duration but gives no accuracy or avoidability bonus.
Even with this skill maxed, it is not even close to being in the same
maplestory mesos league as Power Guard and is why Spearmen/Dark Knights in Maplestory are not considered a soloing class. The other difference is weapon options. Fighters and Pages can both choose between unstable weapons with high max damage, stable weapons with higher min damage, fast
maplestory meso weapons, slow weapons, long reach, short reach, and so on.