shield does blocks in FF XI. and you have a shield skill.
normally you should train the most commonly use weapons.
1h 2hsword and spear for paladins
2h sword 2h spyche for DRK
sword+axe+punching for war
the reason is, not everyone knows how to connect WS of each weapon types..... there are more popula WS combi that everyone kinda knows
1h sword and punching red lotus(burning)>combo is the most popular renkei that all PT lower then lv 20 will be using.
if you got in and BOOM "I only use spear" and no one knows how to connect a spear WS, you will not be taking any part in renkei. and miss the fun. make the whole PT less effective. (1 reason why RNG is hard to get in PT... no one really knows how to connect bows/guns WS)
some other situational, if you are fihgting a magic casting monsters, PLD will have to use 1h and DRK will have to use 2h for the bashing.