Some weapons I've not seen well iplemented in other games include:
whips (unique damage type; ineffect against armor but could have better range and stuff like poison)
spears (better range, higher damage but ineffective against armor)
halbred (heavy slower swing, ....)
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I was going to name a few more but to be honest I don't know enough about how you implemented combat to make effective comments. For example (i believe oringal sin is real time) but do you ahve gun powder? Does distance between combatants play a role in your tactics do you have guard funtions and does positioning of party members matter (i.e, weapons with reach, front row, guard, ...)
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Simply adding additional weapon types seems kind of weak with regards to time spent vs game benefit unless the weapons provide a real advantage/disadvantage that make the player use them in some cases (in this situation I better use the spear but in that situation the sword is clearly better).