Rapier is the main choice of 1st chaotic because it is a general weapon.Good for slayer/bosshunting/activities(such as barrows).The other dungeon items mentioned are usefull for specific reasons. Crossbow,rigour-ranging bosshunting(arma/nex),maul is most usefull for few activities(waterfiends/TDS),arcane stream is mostly used for dks/barrows/training magic(be it through slayer or camping).Haven't used the stream since I got 99 mage. tl:dr: Rapier is a general weapon and it is going to be a favourite first choice for dungeon equipment.