The Langdebeve, in the form of the "Bosom Cleaver" weapon, is the first Heavy Mace blade and the tenth guaranteed blade available without drops (after Glaive and before Guisarme and Wizard Staff, tied for eleventh). It is a Long Weapon, and like all Heavy Maces, has a range of four. Range, especially for melee weapons, does not feature prominently in other games, but in Vagrant Story, almost all attackers either hit and run or in the case of bosses, are extremely large. Long Weapons are able to hit more locations on the large enemies from a single spot, and can be more reliably counted on to be able to attack the ones that run away, before they move out of range.
Damage Points and Phantom Points among other things, add to total damage. Long Weapons also have comparatively more DP and PP than Short Weapons do; Langdebeve has more of either than any of the other Starting Weapons.
Whichever weapons are chosen at the start of the game will acquire a great deal of Class bonuses, so it is worthwhile searching for a good combine target. As the tenth of 12 Starting Weapons, though, and with its best Grip not available until later, combinations with other Starting Weapons gain a lot of value. Like most of the other Starting Weapons, Langdebeve is incapable of a Progression, a superior combinations with the following Heavy Mace Tier; it can only devolve higher-Tier Heavy Mace blades. Since Heavy Mace is at the very beginning of the Design Prevalence chain, the "Bosom Cleaver" blade's BRONZE material will be transferred to any combination with any other Design.
With so few weapons to choose from at the start of the game, it is likely that the "Bosom Cleaver" blade will acquire a great deal of Class bonuses, so it is worthwhile searching for a good combine target. One possibility is to combine the Langdebeve with the Gastraph Bow Starting Weapon, preserving both bonuses to an extent (or fully, if the bonuses are different Classes and equal in value, see All High). The result is a Battle Knife, a Progressive blade; it combines with the admittedly very rare Dirk (only one spawn which is replaced before Ashley leaves the Catacombs). Or the Goblin Club can combine with the Langdebeve to make a Battle Knife. the Gastraph Bow can also be used with a Langdebeve Starting Weapon. The Langdebeve must compete for the Gastraph Bow with the Hand Axe and Goblin Club, both of which combine with it to make the Progressive Broad Sword.
The Langdebeve blade itself is acquired in the Alchemists' Laboratory in the Sanctum; like most of the other guaranteed Starting Weapons, it comes from a chest. It is the reward for defeating two Skeleton Knights and possibly a HP-triggered Poison Slime.
Langdebeve, like all of the eight Heavy Maces, is Blunt Type. The Sand Face it comes with is Edged type and should be replaced with the Czechan Type grip. However, there is little option other than to wait until Town Center West for it. The Czechan Type is a 100% drop from Bejart, one of the Crimson Blades accompanying Duane at Tircolas Flow in Town Center West. There is a One-armed Ghoul in the Sanctum's Theology Classroom that drops it at 25/255; however it does not spawn until Ashley has entered Town Center West. Since Mace weapons and the Staff that Bejart drops are also optimized with Blunt-type grips, it may be worth going back.
Class, Affinity, Type, Damage Points and Phantom Points are all divided by four hundred and then multiplied by total Strength to determine Damage (Crossbow Phantom Points are divided by 800). For example, Czechan Type has eight Blunt and four Edged, for up to 2% times the value of Strength, compared with 3.75% for Minor Elemental gems such as Sylphid Topaz, and the same for Minor Nemesis gems such as Iocus. Langdebeve's Damage Points are 191 at maximum, which would add 47.75% to Strength. Its Phantom Points are 124 at maximum, adding 31% to Strength.