diff --git a/TODO.md b/TODO.md
index badb469d..72a92578 100644
--- a/TODO.md
+++ b/TODO.md
@@ -29,7 +29,6 @@
 ## PSOBB
 
 - Fix some edge cases on the BB proxy server (e.g. Change Ship)
-- Implement less-common subcommands
-    - 6xD8: Add S-rank weapon special
+- Test all quest item subcommands
 - Check if Commander Blade effect works and implement it if not
 - Implement story progress flags for unlocking quests
diff --git a/src/CommandFormats.hh b/src/CommandFormats.hh
index d36aa99f..842a5fd6 100644
--- a/src/CommandFormats.hh
+++ b/src/CommandFormats.hh
@@ -5715,10 +5715,10 @@ struct G_PaganiniPhotonDropExchange_BB_6xD7 {
 struct G_AddSRankWeaponSpecial_BB_6xD8 {
   G_ClientIDHeader header;
   ItemData unknown_a1; // Only data1[0]-[2] are used
-  le_uint32_t unknown_a2 = 0;
-  le_uint32_t unknown_a3 = 0;
-  le_uint16_t unknown_a4 = 0;
-  le_uint16_t unknown_a5 = 0;
+  le_uint32_t item_id = 0;
+  le_uint32_t special_type = 0;
+  le_uint16_t success_function_id = 0;
+  le_uint16_t failure_function_id = 0;
 } __packed__;
 
 // 6xD9: Momoka item exchange (BB; handled by server)
diff --git a/src/QuestScript.cc b/src/QuestScript.cc
index eef1a577..3fe2eb95 100644
--- a/src/QuestScript.cc
+++ b/src/QuestScript.cc
@@ -823,7 +823,7 @@ static const QuestScriptOpcodeDefinition opcode_defs[] = {
     {0xF953, "bb_swap_item", {INT32, INT32, INT32, INT32, INT32, INT32, SCRIPT16, SCRIPT16}, F_V4 | F_ARGS}, // Sends 6xD5
     {0xF954, "bb_check_wrap", {INT32, REG}, F_V4 | F_ARGS},
     {0xF955, "bb_exchange_pd_item", {INT32, INT32, INT32, LABEL16, LABEL16}, F_V4 | F_ARGS}, // Sends 6xD7
-    {0xF956, "bb_exchange_pd_srank", {INT32, INT32, INT32, INT32, INT32, INT32, INT32}, F_V4 | F_ARGS}, // Sends 6xD8
+    {0xF956, "bb_exchange_pd_srank", {INT32, INT32, INT32, INT32, INT32, LABEL16, LABEL16}, F_V4 | F_ARGS}, // Sends 6xD8; argsA[0] is item ID; argsA[1]-[3] are item.data1[0]-[2]; argsA[4] is special type; argsA[5] is success label; argsA[6] is failure label
     {0xF957, "bb_exchange_pd_percent", {INT32, INT32, INT32, INT32, INT32, INT32, LABEL16, LABEL16}, F_V4 | F_ARGS}, // Sends 6xDA
     {0xF958, "bb_exchange_ps_percent", {INT32, INT32, INT32, INT32, INT32, INT32, LABEL16, LABEL16}, F_V4 | F_ARGS}, // Sends 6xDA
     {0xF959, "bb_set_ep4_boss_can_escape", {INT32}, F_V4 | F_ARGS},
diff --git a/src/ReceiveSubcommands.cc b/src/ReceiveSubcommands.cc
index 838c588f..2bd1214e 100644
--- a/src/ReceiveSubcommands.cc
+++ b/src/ReceiveSubcommands.cc
@@ -2531,7 +2531,7 @@ static void on_wrap_item_bb(shared_ptr<Client> c, uint8_t, uint8_t, const void*
   }
 }
 
-static void on_photon_drop_exchange_bb(shared_ptr<Client> c, uint8_t, uint8_t, const void* data, size_t size) {
+static void on_photon_drop_exchange_for_item_bb(shared_ptr<Client> c, uint8_t, uint8_t, const void* data, size_t size) {
   auto l = c->require_lobby();
   if (l->is_game() && (l->base_version == Version::BB_V4)) {
     const auto& cmd = check_size_t<G_PaganiniPhotonDropExchange_BB_6xD7>(data, size);
@@ -2553,7 +2553,41 @@ static void on_photon_drop_exchange_bb(shared_ptr<Client> c, uint8_t, uint8_t, c
       send_quest_function_call(c, cmd.success_function_id);
 
     } catch (const exception& e) {
-      c->log.warning("Quest Photon Drop exchange failed: %s", e.what());
+      c->log.warning("Quest Photon Drop exchange for item failed: %s", e.what());
+      send_quest_function_call(c, cmd.failure_function_id);
+    }
+  }
+}
+
+static void on_photon_drop_exchange_for_s_rank_special_bb(shared_ptr<Client> c, uint8_t, uint8_t, const void* data, size_t size) {
+  auto l = c->require_lobby();
+  if (l->is_game() && (l->base_version == Version::BB_V4)) {
+    const auto& cmd = check_size_t<G_AddSRankWeaponSpecial_BB_6xD8>(data, size);
+
+    try {
+      auto p = c->game_data.character();
+
+      static const array<uint8_t, 0x10> costs({60, 60, 20, 20, 30, 30, 30, 50, 40, 50, 40, 40, 50, 40, 40, 40});
+      uint8_t cost = costs.at(cmd.special_type);
+
+      size_t payment_item_index = p->inventory.find_item_by_primary_identifier(0x031000);
+      // Ensure weapon exists before removing PDs, so inventory state will be
+      // consistent in case of error
+      p->inventory.find_item(cmd.item_id);
+
+      auto payment_item = p->remove_item(p->inventory.items[payment_item_index].data.id, cost, false);
+      send_destroy_item(c, payment_item.id, cost);
+
+      auto item = p->remove_item(cmd.item_id, 1, false);
+      send_destroy_item(c, item.id, cost);
+      item.data1[2] = cmd.special_type;
+      p->add_item(item);
+      send_create_inventory_item(c, item);
+
+      send_quest_function_call(c, cmd.success_function_id);
+
+    } catch (const exception& e) {
+      c->log.warning("Quest Photon Drop exchange for S-rank special failed: %s", e.what());
       send_quest_function_call(c, cmd.failure_function_id);
     }
   }
@@ -2622,7 +2656,6 @@ static void on_photon_crystal_exchange_bb(shared_ptr<Client> c, uint8_t, uint8_t
     size_t index = p->inventory.find_item_by_primary_identifier(0x031002);
     auto item = p->remove_item(p->inventory.items[index].data.id, 1, false);
     send_destroy_item(c, item.id, 1);
-    // TODO: Should we disable drops here?
   }
 }
 
@@ -3008,8 +3041,8 @@ SubcommandDefinition subcommand_definitions[0x100] = {
     /* 6xD4 */ {0x00, 0x00, 0xD4, nullptr},
     /* 6xD5 */ {0x00, 0x00, 0xD5, on_quest_exchange_item_bb},
     /* 6xD6 */ {0x00, 0x00, 0xD6, on_wrap_item_bb},
-    /* 6xD7 */ {0x00, 0x00, 0xD7, on_photon_drop_exchange_bb},
-    /* 6xD8 */ {0x00, 0x00, 0xD8, nullptr},
+    /* 6xD7 */ {0x00, 0x00, 0xD7, on_photon_drop_exchange_for_item_bb},
+    /* 6xD8 */ {0x00, 0x00, 0xD8, on_photon_drop_exchange_for_s_rank_special_bb},
     /* 6xD9 */ {0x00, 0x00, 0xD9, on_momoka_item_exchange_bb},
     /* 6xDA */ {0x00, 0x00, 0xDA, on_upgrade_weapon_attribute_bb},
     /* 6xDB */ {0x00, 0x00, 0xDB, nullptr},