Not skills, stats. Becoming a vampire causes your strength, agility, and toughness to double, but you can no longer increase any physical stats after that. It also prevents physical stat rust, however, so they'll never get weaker, either.
The full effects are as follows:
[I_EFFECT:ADD_SYNDROME]
[IE_TARGET:A]
[IE_IMMEDIATE]
[IE_ARENA_NAME:Vampire]
[SYNDROME]
[SYN_CLASS:VAMPCURSE]
[CE_ADD_TAG:BLOODSUCKER:NO_AGING:STERILE:NOT_LIVING:NOEXERT:NOPAIN:NOBREATHE:NOSTUN:NONAUSEA:NO_DIZZINESS:NO_FEVERS:PARALYZEIMMUNE:NO_EAT:NO_DRINK:NO_SLEEP:NO_PHYS_ATT_GAIN:NO_PHYS_ATT_RUST:START:0]
[CE_PHYS_ATT_CHANGE:STRENGTH:200:0:AGILITY:200:0:TOUGHNESS:200:0:START:0]
[CE_MATERIAL_FORCE_MULTIPLIER:MAT_MULT:NONE:NONE:1:2]
[CE_BODY_MAT_INTERACTION:MAT_TOKEN:RESERVED_BLOOD:START:0]
[CE:INTERACTION:VAMPIRE_CURSE]
[CE:SYNDROME_TAG:SYN_INGESTED]
[CE:SYNDROME_TAG:SYN_INJECTED]
[CE_DISPLAY_TILE:TILE:165:4:0:0:START:0:CAN_BE_HIDDEN]
[CE_DISPLAY_NAME:NAME:vampire:vampires:vampiric:START:0:CAN_BE_HIDDEN]
[CE_BP_APPEARANCE_MODIFIER:START:0:BP:BY_CATEGORY:TOOTH:APPEARANCE_MODIFIER:LENGTH:150]
[CE:COUNTER_TRIGGER:DRINKING_BLOOD:1:NONE:REQUIRED]
Most relevant are the [CE_ADD_TAG] line, the [CE_PHYS_ATT_CHANGE] line, and the [CE_MATERIAL_FORCE_MULTIPLIER] line.
Also, I think not double-posting is generally appreciated. Use the edit button if you realize there's something else you want to add and nobody else has posted in the meantime.