The /sea feature was implemented in patch 1.21. I don't remember the details or how it stacks agains XI's. But is there. I think you activate it by typing /search. I don't remember quite well, at job atm, so unable to confirm!
Edit: FOUND IT!
•[dev1333] The text command /search (/who) has been added for performing player searches.
For example, the following command line performs a search for pugilists between levels 10 and 20, whose status is Online.
/search online pgl 10-20
The following conditions can be specified:
* All conditions are selected when none are designated.
•Player Status
ONLINE (logged in) / INVITE (seeking invite) / PARTY (currently in party)
Ex.) /search invite
•Class
DOW (Disciples of War) / PGL (pugilist) / GLA (gladiator) / MRD (marauder) / ARC (archer) / LNC (lancer) / DOM (Disciples of Magic) / THM (thaumaturge) / CNJ (conjurer) / DOH (Disciples of the Hand) / WDK (woodworker) / BSM (blacksmith) / ARM (armorer) / GSM (goldsmith) / LTW (leatherworker) / WVR (weaver) / ALC (alchemist) / CUL (culinarian) / DOL (Disciples of the Land) / MIN (miner) / BTN (botanist) / FSH (fisher)
Ex.) /search con
•Job
Search for only those players who have obtained the jobs affiliated with the designated class.
Ex.) /search job
•Level
•XX: Search for exact match.
•XX-YY or XX
Ex.) /search 45-50
* Omitting a value will result in a search for players within 5 levels of your own.
•Grand Company Affiliation
GCL (Maelstrom) / GCU (Immortal Flames) / GCG (Order of the Twin Adder) / GCN (no affiliation)
* All conditions are selected when none are designated.
Ex.) /search gcg
•Area
Search for players in the designated area.
Ex.) /search [South Shroud]
*As is the case with all subcommands, place names with more than one word need to be in brackets.
•Language
EN (English) / JA (Japanese) / FR (French) / DE (German)
Ex.) /search en
If the Search interface is open when /search is executed, the conditions on the intertace will change to reflect those specified in the text command.